add_action( 'init', 'listing_search_url' );
  function listing_search_url()
  {
    add_rewrite_tag('%type%', '([^&]+)');
    add_rewrite_tag('%search_location%', '([^&]+)');
    add_rewrite_rule(
        '^custom(/([^/]+))?/(/([^/]+))?/?',
        'index.php?page_id=23&type=$matches[2]&search_location=$matches[4]',
        'top'
    );
    flush_rewrite_rules();
  }

function wpd_foo_get_param() {
    if( false !== get_query_var( 'search_location' ) ){
        $_GET['search_location'] = get_query_var( 'search_location' );
    }
}
add_action( 'parse_query', 'wpd_foo_get_param' );

add_action( 'parse_query', 'listing_get_query_vars' );
 function listing_get_query_vars() {
     //if you use - _ + on your url the form just recive a space
    if(!empty( get_query_var( 'search_location' )) ){
        $_GET['search_location'] = str_replace(array('-','_','+'),' ',get_query_var( 'search_location' ));
    }
}

function wpd_foo_get_param() {
    if( false !== get_query_var( 'search_location' ) ){
        $_GET['search_location'] = get_query_var( 'search_location' );
    }
}
add_action( 'parse_query', 'wpd_foo_get_param' );