Remove JSON Data from Form Post With Web Hook

We set up a landing page on Unbounce and we need it to post to a 3rd party lead distribution system called Cake. Cake only accepts XML and the way the Unbounce form works with the webhook is that the string first has the JSON data and then the XML data later in the string. The problem is cake only allows a certain amount of characters with a post so the XML data never gets read and the form submission does not get into the cake system. Is there a script or way to strip out the JSON data with a form post using the webhook or make it show up last in the string sent?