Sounds like he better make DANG sure it is a non-detachable converter dolly before he loads it front to back and starts crossing old wooden bridges. 

Sounds like the kind of law where if you ask two different Dot officers you're gonna get two different answers.

Still, combining all of the headaches of a dumping a hopper with the slow travel speed of a tractor (yes he is talking about a fast tractor but its still slow) doesn't seem like that great of an idea to me.