This Editor extension class that I extended to include ScriptableObjects allows you to get and set fields on a Component or ScriptableObject that is contained within a SerializedProperty

SerializedPropertyExtensions.cs

// --------------------------------------------------------------------------------------------------------------------
// <author>
//   HiddenMonk
//   http://answers.unity3d.com/users/496850/hiddenmonk.html
//   
//   Johannes Deml
//   send@johannesdeml.com
//
//   Eris Koleszar
//   me@eris.codes
// </author>
// --------------------------------------------------------------------------------------------------------------------

using System.Collections.Generic;
using System.Linq;

namespace Supyrb
{
    using System;
    using UnityEngine;
    using UnityEditor;
    using System.Reflection;

    /// <summary>
    /// Extension class for SerializedProperties
    /// See also: http://answers.unity3d.com/questions/627090/convert-serializedproperty-to-custom-class.html
    /// </summary>
    public static class SerializedPropertyExtensions
    {
        /// <summary>
        /// Get the object the serialized property of a Component holds by using reflection
        /// </summary>
        /// <typeparam name="T">The object type that the property contains</typeparam>
        /// <param name="property"></param>
        /// <returns>Returns the object type T if it is the type the property actually contains</returns>
        public static T GetValueFromComponent<T>(this SerializedProperty property)
        {
            return GetNestedObject<T>(property.propertyPath, GetSerializedPropertyRootComponent(property));
        }

        /// <summary>
        /// Get the object the serialized property of a ScriptableObject holds by using reflection
        /// </summary>
        /// <typeparam name="T">The object type that the property contains</typeparam>
        /// <param name="property"></param>
        /// <returns>Returns the object type T if it is the type the property actually contains</returns>
        public static T GetValueFromScriptableObject<T>(this SerializedProperty property)
        {
            return GetNestedObject<T>(property.propertyPath, GetSerializedPropertyRootScriptableObject(property));
        }

        /// <summary>
        /// Set the value of a field of the property with the type T on a Component
        /// </summary>
        /// <typeparam name="T">The type of the field that is set</typeparam>
        /// <param name="property">The serialized property that should be set</param>
        /// <param name="value">The new value for the specified property</param>
        /// <returns>Returns if the operation was successful or failed</returns>
        public static bool SetValueOnComponent<T>(this SerializedProperty property, T value)
        {

            object obj = GetSerializedPropertyRootComponent(property);
            //Iterate to parent object of the value, necessary if it is a nested object
            string[] fieldStructure = property.propertyPath.Split('.');
            for (int i = 0; i < fieldStructure.Length - 1; i++)
            {
                obj = GetFieldOrPropertyValue<object>(fieldStructure[i], obj);
            }
            string fieldName = fieldStructure.Last();

            return SetFieldOrPropertyValue(fieldName, obj, value);

        }

        /// <summary>
        /// Set the value of a field of the property with the type T on a ScriptableObject
        /// </summary>
        /// <typeparam name="T">The type of the field that is set</typeparam>
        /// <param name="property">The serialized property that should be set</param>
        /// <param name="value">The new value for the specified property</param>
        /// <returns>Returns if the operation was successful or failed</returns>
        public static bool SetValueOnScriptableObject<T>(this SerializedProperty property, T value)
        {

            object obj = GetSerializedPropertyRootScriptableObject(property);
            //Iterate to parent object of the value, necessary if it is a nested object
            string[] fieldStructure = property.propertyPath.Split('.');
            for (int i = 0; i < fieldStructure.Length - 1; i++)
            {
                obj = GetFieldOrPropertyValue<object>(fieldStructure[i], obj);
            }
            string fieldName = fieldStructure.Last();

            return SetFieldOrPropertyValue(fieldName, obj, value);

        }

        /// <summary>
        /// Get the component of a serialized property
        /// </summary>
        /// <param name="property">The property that is part of the component</param>
        /// <returns>The root component of the property</returns>
        public static Component GetSerializedPropertyRootComponent(SerializedProperty property)
        {
            return (Component)property.serializedObject.targetObject;
        }

        /// <summary>
        /// Get the scriptable object of a serialized property
        /// </summary>
        /// <param name="property">The property that is part of the scriptable object</param>
        /// <returns>The root scriptable object of the property</returns>
        public static ScriptableObject GetSerializedPropertyRootScriptableObject(SerializedProperty property)
        {
            return (ScriptableObject)property.serializedObject.targetObject;
        }

        /// <summary>
        /// Iterates through objects to handle objects that are nested in the root object
        /// </summary>
        /// <typeparam name="T">The type of the nested object</typeparam>
        /// <param name="path">Path to the object through other properties e.g. PlayerInformation.Health</param>
        /// <param name="obj">The root object from which this path leads to the property</param>
        /// <param name="includeAllBases">Include base classes and interfaces as well</param>
        /// <returns>Returns the nested object casted to the type T</returns>
        public static T GetNestedObject<T>(string path, object obj, bool includeAllBases = false)
        {
            foreach (string part in path.Split('.'))
            {
                obj = GetFieldOrPropertyValue<object>(part, obj, includeAllBases);
            }
            return (T)obj;
        }

        public static T GetFieldOrPropertyValue<T>(string fieldName, object obj, bool includeAllBases = false, BindingFlags bindings = BindingFlags.Instance | BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic)
        {
            FieldInfo field = obj.GetType().GetField(fieldName, bindings);
            if (field != null) return (T)field.GetValue(obj);

            PropertyInfo property = obj.GetType().GetProperty(fieldName, bindings);
            if (property != null) return (T)property.GetValue(obj, null);

            if (includeAllBases)
            {

                foreach (Type type in GetBaseClassesAndInterfaces(obj.GetType()))
                {
                    field = type.GetField(fieldName, bindings);
                    if (field != null) return (T)field.GetValue(obj);

                    property = type.GetProperty(fieldName, bindings);
                    if (property != null) return (T)property.GetValue(obj, null);
                }
            }

            return default(T);
        }

        public static bool SetFieldOrPropertyValue(string fieldName, object obj, object value, bool includeAllBases = false, BindingFlags bindings = BindingFlags.Instance | BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic)
        {
            FieldInfo field = obj.GetType().GetField(fieldName, bindings);
            if (field != null)
            {
                field.SetValue(obj, value);
                return true;
            }

            PropertyInfo property = obj.GetType().GetProperty(fieldName, bindings);
            if (property != null)
            {
                property.SetValue(obj, value, null);
                return true;
            }

            if (includeAllBases)
            {
                foreach (Type type in GetBaseClassesAndInterfaces(obj.GetType()))
                {
                    field = type.GetField(fieldName, bindings);
                    if (field != null)
                    {
                        field.SetValue(obj, value);
                        return true;
                    }

                    property = type.GetProperty(fieldName, bindings);
                    if (property != null)
                    {
                        property.SetValue(obj, value, null);
                        return true;
                    }
                }
            }
            return false;
        }

        public static IEnumerable<Type> GetBaseClassesAndInterfaces(this Type type, bool includeSelf = false)
        {
            List<Type> allTypes = new List<Type>();

            if (includeSelf) allTypes.Add(type);

            if (type.BaseType == typeof(object))
            {
                allTypes.AddRange(type.GetInterfaces());
            }
            else
            {
                allTypes.AddRange(
                        Enumerable
                        .Repeat(type.BaseType, 1)
                        .Concat(type.GetInterfaces())
                        .Concat(type.BaseType.GetBaseClassesAndInterfaces())
                        .Distinct());
            }

            return allTypes;
        }
    }
}