How to create a Full RSS feed (secret URL) for certain users, short for the rest [closed]

A “secret” full text feed

Here’s a demo plugin that gives you a full text feed at:

example.tld/secretfeed/

Just remember to flush the rewrite rules, e.g. by visiting the Settings/Permalinks page:

<?php
/**
 * Plugin Name: Secret Full Text Feed
 * Plugin URI:  http://wordpress.stackexchange.com/a/208724/26350
 */
add_action( 'init', function()
{
    add_feed( 'secretfeed', 'do_feed_rss2' );
});

add_action( 'pre_get_posts', function( \WP_Query $q )
{
    if( $q->is_feed( 'secretfeed' ) )
        add_filter( 'option_rss_use_excerpt', '__return_false' );

} );

You can then adjust the secretfeed slug to your needs.