This gets fuzzy in a hurry, cause a car under tow is not considered a "trailer" under the letter of the law. There are special regs for towed cars.
The most important law, though, is Newton's Law concerning bodies in motion. Even 3020 lbs of extra, unbraked weight is significant, and whatever you are towing it with, it's brake system is NOT sized to handle the extra towed weight, The brakes in the motorhome are designed to stop it's own weight (GVWR), and nothing more. You really need brakes on the toad.