As many here know, I have been researching this issue for over twenty years. this is what I have found:
1. Federal Motor Vehicle Safety Standards (FMVSS) state that you must be able to stop any combination of vehicles (Can anybody honestly say that a motorhome with towed vehicle is NOT a "Combination of vehicles"?) within 40 feet from 20 MPH on a level, dry, clean, hard surface. If your rig can do that, you are within the limits set by FMVSS.
2. Many states have incorporated this braking performance requirement into their own State Laws/Codes/regulations. One state (CA) gives more room (45 feet).
3. Many states have a legal definition of "trailer" that obviously does not include a towed motor vehicle that was not originally designed to be towed, is intended to carry people, and is capable of being driven using its own motive power.
4. Braking requirements do not have "Reciprocity". You must meet the requirements of the jurisdiction in which you are currently operating.
5. While brakes on any towed load is a good idea, in many areas of the country it is not a legal requirement, IF the combination of vehicles meets the braking performance requirements spelled out in the law.
All that being said, I admit to being one of the "no braking" crowd. I towed assorted Jeep Wranglers, a Dodge Ram 1500, and a PT Cruiser on a dolly, all with no brakes. Oh, yeah, and an ATV on a single axle trailer, also with no brakes.
Nothing bent, nothing broke, nobody was injured or died.