possibly needing additional hook

in this file:
woocommerce-shipstation-integration/includes/api-requests/class-wc-shipstation-api-shipnotify.php

I need to force a specific order status scenario, by modifying:
$order->update_status( WC_ShipStation_Integration::$shipped_status );

with

if($order->get_payment_method() == 'check' || $order->get_payment_method() == 'cheque') {
    $order->update_status('pending-payment');
} else {
    $order->update_status( WC_ShipStation_Integration::$shipped_status );
}

Can you suggest a way I could accomplish this without modifying your code base, or is it possible for you make some sort of hook in the plugin that would allow me to do so?

Thank you!