DOT doesn't use the vehicle GVWR or GCWR.
GCWR isn't stickered on any vehicle.
DOT also won't use the vehicle GVWR to determine a overloaded vehicle.
And DOT doesn't use the vehicle mfg tow rating for anything.
Any vehicle on the road can be weighed.
If your stopped for a over weight condition it can go like this paste and copy from a state motor vehicle size and weight commander who was asked about exceeding GVWR/GCWR and replied; snipped for length;
...."Vehicle Code (CVC) does not contain a law that
specifically limits the amount of weight a vehicle may tow based on the
towing vehicle GVWR or GCWR. There are, however, laws that limit the
amount a vehicle may tow based on other criteria.
".....prohibits the loading of tires above the maximum load rating marked on the tire,
or if unmarked the maximum load rating as specified in the applicable
Federal Motor Vehicle Safety Standard, or in a publication furnished to
the public by the tire manufacturer. This would most likely happen in
the case of a pickup truck towing a large fifth wheel travel trailer, as
those types of trailers tend to transfer a larger portion of their
weight to the last axle of the towing unit causing that axle to exceed
the tire load limits."
I towed for a living some years back. I also used my one ton DRW trucks to pull a rv trailer or carry a heavy truck camper. Because of the dot/MC number I had to pull into all scale houses. Let them know your pulling your own Rv for recreational purposes......you had better be able to prove the rv is yours. If its registered to someone else they will assume your hauling for hire. That can mean lots of time in the impound lane explaining things.
Some haulers remove their magnetic signs when towing or carrying their RVs. Check with your dot guys on what you may run into.