Woo Subscriptions- Modify Trial-Expire and Next-Payment Date

/**
 * FREE TRIAL EXPIRATION DATE for MONTHLY-ONGOING
 * Quarterly needs different calc !
 * for Ongoing club subscriptions (monthly and quarterly), which charge on the 1st of the next month,
 * NOT immediately (as other subscriptions do)
 *
 * @hook  in classes/class-wc-subscriptions-manager.php#1855
 * @ref  http://www.onlineconversion.com/unix_time.htm
 */
add_filter ('woocommerce_subscription_calculated_trial_expiration_date','tz_wc_filter2',10,2);
function tz_wc_filter2($expiration_date, $subscription_key) {

    // TODO: if($subscription_length == 0){ // ongoing!
    // how to find that here??

    date_default_timezone_set('America/Los_Angeles');
    $now = date('Y-m-d');
    $d = new DateTime( $now );
    $d->modify( 'last day of this month' );
    $trial_expire_date = $d->format( 'Y-m-d H:i:s' );
    $trial_expire_unix = strtotime($trial_expire_date);
    $expiration_date = $trial_expire_unix;
    return $expiration_date;
}

/**
 * NEXT PAYMENT DATE for MONTHLY-ONGOING
 * Quarterly needs different calc !
 * for Ongoing club subscriptions (monthly and quarterly), which charge on the 1st of the next month,
 * not immediately (as other subscriptions do)
 *
 * @hook  in classes/class-wc-subscriptions-order.php#488
 */
add_filter ('woocommerce_subscriptions_calculated_next_payment_date','tz_wc_filter3',10,3);
function tz_wc_filter3($next_payment,$product_id,$order) {

    $product_meta = get_post_meta($order);
    $subscription_length = $product_meta['_subscription_length']['0'];
    if($subscription_length == 0){ // ongoing!

        date_default_timezone_set('America/Los_Angeles');
        $now = date('Y-m-d');
        $d = new DateTime( $now );
        $d->modify( 'first day of next month' );
        $next_payment_date = $d->format( 'Y-m-d H:i:s' );
        $next_payment_unix = strtotime($next_payment_date);
        $next_payment = $next_payment_unix;
    }
    return $next_payment;
}