A Paid Memberships Pro Register Helper Extension Example (pmpro-register-helper-fields)

pmpro-register-helper-fields.php

<?php
/*
Plugin Name: Register Helper Example
Plugin URI: http://www.paidmembershipspro.com/wp/pmpro-customizations/
Description: Register Helper Initialization Example
Version: .1
Author: Stranger Studios
Author URI: http://www.strangerstudios.com
*/
//we have to put everything in a function called on init, so we are sure Register Helper is loaded
function my_pmprorh_init()
{
    //don't break if Register Helper is not loaded
    if(!function_exists("pmprorh_add_registration_field"))
    {
        return false;
    }

    //define the fields
    $fields = array();
    $fields[] = new PMProRH_Field(
        "Auditions",              // input name, will also be used as meta key
        "checkbox",                 // type of field
        array(
            //"text"=>"Checkbox Text", //not usually needed but if used, this will change the text next to the checkbox and the name will be put on the left using an HTML label tag instead
            "class"=>"myclass", // custom class for custom CSS if needed
            "profile"=>true,    // Should this field also be shown in the profile? Valid values are true, false, “only”, or “only_admin”
        ));


    $fields[] = new PMProRH_Field(
        "Stage Management",         // input name, will also be used as meta key
        "checkbox",                 // type of field
        array(
            "profile"=>true,
        ));
    $fields[] = new PMProRH_Field(
        "Backstage Crew",
        "checkbox",
        array(
            "profile"=>true,
        ));
    $fields[] = new PMProRH_Field(
        "Publicity",
        "checkbox",
        array(
            "profile"=>true,
        ));

    //add the fields into a new checkout_boxes are of the checkout page
    foreach($fields as $field)
        pmprorh_add_registration_field(
            "checkout_boxes", // location on checkout page
            $field            // PMProRH_Field object
        );

    //that's it. see the PMPro Register Helper readme for more information and examples.
}
add_action("init", "my_pmprorh_init");

How to make those checkbox checked by default?

Sorry @kingvish, just now saw this and not sure why. Best I can see is https://gist.github.com/andrewlimaza/82417f361ff99d800346f55dfe93e33b who is creating a checkbox as HTML. I'm not sure if there's a better way yet or not!