Nick, I've seen boats and single axle trailers being towed behind 5ers. The hitch and your 5er frame has to be capable of towing a 4,000 to 5,000 pound vehicle. Then, like mentioned, length of all attached will need to be within a certain length per State.
I like the idea of mhs4771, where you place a smaller vehicle on the back of a tractor (heavy duty truck) and tow your 5er. I think it's cool
!