Towing without a car braking system??

About 12 years ago MY TOWED BROKE AWAY FROM ME! Yup, it really happened. The mounting bracket on the Saturn Vue (custom made by the hitch shop) failed and as I was stopping at a light one a lightly traveled road I saw the Saturn slowly begin to pass me on the right. OMG!!! I was able to stop, hop out of the motorhome, open the unlocked car and set the emergency brake before it got too far ahead. (I was 12 years younger then). The shop made it right by me. No one was hurt. Anyway, I now use a ReadyBrake with the Saturn and a we have a new diesel motorhome. I do not have a "brake in use" light or indicator. Seems silly with the ReadyBrake configuration. I probably don't need the auxiliary brake, but I believe it is required in some states, and it is just a safety thing. I would not travel without a "break away brake". You could kill someone.
JMHO

We towed a Mustang convertible for some 6 years without a braking system and never had a problem. My understanding is a braking system is required if the car (trailer) weighs more than 3,000 lbs. The Mustang weighed about that much.

We replaced the Mustang with a Hummer, which weighs about 4,600 lbs, and we use a Roadmaster braking system connected to our air brakes on the coach. It works great.

I was warned by several friends not to use the box type that fits in front of the driver's seat and depends on changes in inertia to detect a braking action and press down on the brake pedal. Apparently, they frequently fail and apply the brakes when not required. Still, a lot of RV owners use these systems. They connect to the power outlet in the dash and can be moved to any towed vehicle, so they don't require any modifications to either vehicle.

It is my understanding that some states require an auxiliary braking system for towed vehicles/trailers. Some have weight minimums other just require it.

Ours is kind of new to us and only towed about 250 miles so far. The towed vehicle brake only came on 2 times for about a second. I figured if I really had a hard braking situation it would engage more and longer. Gain set to 3 on the Patriot. IINM it is law to have one in many states.

Your gross COMBINED vehicle weight rating (GCWR) means that your coach's engine, transmission, and braking system is designed to handle that amount of COMBINED weight, including your coach, your load, and anything in tow.
The towed braking system MAY allow your vehicle to stop a little quicker in an emergency situation.