in pa there is a thing about if a trailer is over 10,000gvw you need a combo licence for truck and trailer. pisses off the rv guys cause the 5th wheel rvs can be 12,000gvw. but the rv guys never get hit so there is either a huge gray area for the rv world or the state cops do not care as of yet.
no rv guy i know with the huge 5th wheel has a combo licence. they get away with it.