Need help with date picker and URL parameters

Hi!

I needs some help with my form.

The idea is to create a booking calendar for a hotel where you choose your arrival date, departure date and how many people are staying.

The problem is that the booking system that shall receive the data has a different syntax for the dates.

This is the booking system:
http://secure.techotel.dk/domino.aspx?hotelid=223774&lang=no

So the URL from the form should then be:
http://secure.techotel.dk/domino.aspx?hotelid=223774&lang=no&p_arr=20190504_0000&p_dep=20190505_0000&p_pax=2

But the form outputs this URL instead:
?p_arr=2019-03-23&p_dep=2019-03-24&p_pax=2

So, how do I change the default date format:
yyyy-mm-dd
to:
yyyymmdd_0000

Preview:
https://preview.webflow.com/preview/datepicker-e4a7d3?utm_source=datepicker-e4a7d3&preview=7902ef311de6ba3fc35b3a11b2e7b48e