As long as the Munchkin code is on the page, you could also copy/paste a forms html code on your non-marketo page (make sure to include IDs and so on). Also add the javascript and so on. You propably need a good programmer for this. But I must say it's not very flexible (e.g. you can't alter the form in Marketo). The best option is what we use at Quintiq. We have our own (progressive) forms on our website, but we manipulated Munchkin to set a form-submit on the thank you page. This works for us. In Marketo I can even see and trigger on that form fill.