ScriptableObjectBase.cs

using System.IO;
using UnityEngine;
using UnityEditor;

namespace SetupTools
{
    public class AbstractSettings<T> : ScriptableObject where T : ScriptableObject
    {
        public static T Load(string assetPath)
        {
            return AssetDatabase.LoadAssetAtPath<T>(assetPath);
        }

        static T CreateDefault(string assetPath)
        {
            T setting = CreateInstance<T>();
            AssetDatabase.CreateAsset(setting, assetPath);
            Debug.Log(string.Format("Created: {0}", assetPath));
            return setting;
        }

        public static T LoadOrCreate(string assetPath)
        {
            if (File.Exists(assetPath)) {
                return Load(assetPath);
            } else {
                return CreateDefault(assetPath);
            }
        }
    }    
}