DOT rules are federal and supposed to be uniform throughout the states,but the states can have other rules over and above the DOT.The keyword is commerce,so when they ask if you make money,laugh at the officer and tell him how much you LOOSE every year.
The other issue is the way a person registers thier tow vehicle.I know some cheapazz guys that register the vehicle as the curb weight instead of the MAX weight and put passenger plates on instead of Commercial plates to save a coupla bucks.If you get pulled into a DOT stop,your likley to get an OVERWEIGHT ticket if your pullin your trailer.
Check with your local DMV & DOT and look at the rules to determine what's best for you.
Also do a search here,we have debated this topic before