So anything with an "open" bed? How about a truck with a removable "camper"? A lot of folks add them to their trucks to enclose the bed, after market parts of course.
Maybe making the removable "camper" standard?
The 1st gen 4 Runner by Toyota had this exact feature, so did some Ford Bronco.
Sounds like a pretty easy law to "bypass". The law is probably against WTO regulations, but no one has yet to complain