As I mentioned above, even DOT officers are lost in lot of DOT laws, so let's not expect too much.
I can chime in about non-commercial registration.
I took my dually for the inspection with big TC and the "weigh fee" got waived.
It did not matter if that was regural bed, flatbed, or utility bed.
That doesn't mean I can take camper off and take it on the road legally. I do have camper shell for such occasions, but would I got pulled over with load of concrete, or manure, I might have lot to explain.
I still own bus conversion that DMV mistakenly registered as "bus"
Even having huge "Private coach" on the cap did not protect me from a ticket "for parking commercial vehicle" in inappropriate spot.
The law is a maze and no matter how much you will try, in real life you will have to brush it somewhere.
Funny part, I called DMV with question and I can haul unlimited weight commercial trailer with non-commercial vehicles and don't have obligation to stop at scales.
That doesn't mean DOT might not have different "opinion" on the subject.
