This topic has come up at our park a couple of times. I am of the opinion that you have to abide by the laws of the state/province you are in as regarding double towing and legal length. I believe tha...
OP...you are correct, concerning the legal double towing, which is a state by state option. Just like speeding, you may get by, in one of the states you mentioned, but best to have a plan, when you have to leave/park second trailer.