Just shove it between the vent and winshield about where the glovebox is. I live in NJ (need both plates) and I've been riding around with both a Euro plate and the plate filler for about a year w/ no problems. I don't even have the U.S. plate in the winshield anymore, it's in the glovebox. If the cop wants to be a dick, he could get you for no front plate and obstruction of view if the plate is in the windshield.