Our government seems bent on making things as unweildingly complex as possible. With the new transportation act opening the door to "replica" imports (It seems relatively restrictive, though it looks as Morgan +4s and Roadsters will fit), wouldn't simple warning placards placed on door jambs or firewall solve the problem?
I'm sure others can add to my thoughts and put it better than I have opined. Things were much simpler in our younger days, eh?