OP has asked if the door sticker is law, it is not, it his paid for registration that is the law.
Just as I've stated many times. My 2000 C2500 has a paid for registration of 8000 lbs. I am legal to 8000 lbs. IF I run down that road at the 8600 lb door sticker, I am illegal, and over weight by 600lbs!
My twin son's, one has a Toyota Tacoma, the other a Chevrolet 1500. Both.also have 8000 lb registrations. Both are legal to 8000 lbs. Neither maxes their trucks to this ALL the time. If they go over the door stickers, they are legal! There insurance covers.them! Pretty sole from this states standpoint, would assume, most others are equal, ASSUMING they want federal funds for roads, they can not enforce less.than limits in FBL's.
Marty