It isn't. I have a corporate blanket policy that covers rentals and the vehicle I used to tow (corporate truck). It explicitly excludes liability when in violation of a contract such as the one you sign when renting a U-Haul. Sometimes it's a good idea to play by the rules. Accidents aren't something you can always avoid. Getting hung with a U-Haul trailer and a totalled car (or cars) wouldn't be fun.

My insurance covers what I’m towing. I have 3 trailers but sometimes I need a car hauler. Uhaul insurance covers their trailer which is about $5k.

If your truck can tow 6000lbs they won’t let you take a car that weighs more that 2k. Their trailer weighs 2k so you could have 4K in car wieght.Just saying. If you want to be honest then take a different route. Maybe rent their large box truck to tow a car hauler ..

What they don't know won't hurt them!! I'll roll the dice on all of that. I just wanted to make sure the car fits on the trailer. Whether legal or right.... doesn't matter to me. Sorry. I'm just a blatantly honest person (about what I'm dishonest about).

Dolly won't work. Get their larger trailer (they have 2 sizes). Bring your own straps. The ones that they use that go over the wheels looks well sketchy