I thought it was all based-on door sticker and axle ratings?
To be non CDL:
A dually (or any truck) with a 14k GVWR can pull a trailer with a 12k GVWR.
Dually 13k, trailer 13k.
Dually 12k, trailer 14k.
Dually 11k, trailer 15k.
Dually 10k, trailer 16k.
You still have to be within axle ratings.
I pulled 17k with my 10k rated SRW F250. I only grossed at 24k+ because the truck actually weighs 7,300 lbs. I was over the 10k GVWR on the truck because I was pin heavy based on the load on the trailer. Trailer was rated for 14k+.
If I could have shifted 260 lbs off the pin and onto the trailer, the truck axles would have scaled at 10k and the trailer axles would have scaled at 14,240. All would have been legit for a non CDL load.
If I would have been driving a dually rated at 14k, the empty trailer would have put me over 26k combined. A derated dually would have been much safer.
I had a Class A non CDL for driving air brakes, 26k+ and tractor trailers (fire department). Last time I renewed my license they changed it to a Class E. Truck over 26k and trailer over 10k, non CDL.
I have asked two DOT people if I can still go over 26k combined, non CDL, for personal use. One said "send it". The other said "fire trucks only".