So if you intentionally tow something and are exceeding the GVWR, In California at least they might check the weight of your RV and truck, then charge you with causing the accident due to overloading the truck.
Your insurance company can 'excuse itself' from covering the accident too, leaving you without insurance paying for the accident due to your buying and towing with the wrong vehicle.
Overload the tires and you really "Expect" them to not have a blowout? You can overload a tire by about 50 or 75 pounds, but not really 200 or 400 pounds.
It is much better to buy a dually truck than to overload one. The dually Ford has a 5700 pound cargo rating, without overloading the tires or axle, or brakes, or transmission, or springs, or more importantly the radiator and transmission cooler.
The dually F-350 has a larger capacity cooling system than lessor trucks. Step up to the F-450 cab and chassis, and the radiator and transmission cooler, oil cooler, and such get even larger, with more capacity to cool the engine and transmission while climbing the mountains while towing a 18,500 pound trailer!
So why pick a 2500 series truck to tow a fifth wheel? Pick the 3500 series, or better yet the F-350. Dually might not be required, yet pick that one if you need to carry 5,000+ pounds!
Fred.