Both breeds are pretty rare here so no, I've never heard of the cross.
I cannot imagine why you'd want to do the cross except to get some colour into your Florida Whites but a Mini Lop would be a better choice as they have a meatier frame than Polish.
Florida Whites were originally crosses from albino Dutch, New Zealands, and Polish, so I see that working out. I, of course, would maybe suggest a breed closer in size, like a Havana or Lilac, if you're looking for other colors.
I guess my only reason is to put a little size into the polish so if they don't sell they can feed something or someone. And to put a little color into the Florida's for 'unique ness' as pets