Hi,
I think that many states have a 'reasonable' law about towing a light car with a heavy motorhome. I think that the limit is 30% of the motorhome weight to tow without a braking system in that state. So a 15,000 pound motorhome like yours could safely tow up to 30% or 4,500 pounds. Of course Ford has other ideas on what can be safely towed. Ford says that the brakes on the RV chassis are rated at the RV GVWR + 1,500 pounds of unbraked trailer.
Most RV's are not running at their maximum GVWR, so if the GVWR is say 17,000 pounds (like mine is) and your scale weight is only say 15,800 pounds (like my 30' Bounder) you would have 1,200 pounds below the GVWR. Then add the 1,500 pounds that Ford lets you tow unbraked, and you can tow up to about 2,700 pounds without braking system.
Is it safer to tow with brakes? Sure. Can you get in trouble without brakes? Perhaps.
What did I do? Well I installed a cruise control from a junkyard car in my Ford Edge. It is a 4,200 pound car, with auto transmission that is fine with being towed 4 wheels down. I bought it specifically to tow behind my Bounder.
The CC motor uses vacuum to pull the cable. The cable is attached to the brake pedal arm, and pulls with about 5 square inches of surface area, and has about 20" vacuum, or about 10 PSI X 5 square inches = 50 foot pounds max force. This effectively pulls my brake pedal to the floor, and does not pull hard enough to cause the brakes to lock up in gravel, or overheat the brakes on a long downgrade. Yes I can adjust the pressure of the braking too. Just attach the cable closer to the brake pedal to increase the brake pressure, while mounting the cable higher on the pedal arm will decrease the amount of brake effort.
I also tied my Edge power brakes into the Bounder engine vacuum, so I have power brakes. I used a 50' air hose from the Bounder air intake to the rear bumper, then a quick disconnect air fitting to the car, where I used the remaining 6' or so of air hose to attach to the car. I put a tee into the brake vacuum line with 2 check valves so that air flows correctly, and I still have power brakes should the car engine stop for whatever reason while driving the car.
Good luck!
Fred.
PS: I set up my braking system for about $35 in junkyard parts. I also used a 3 way vacuum valve so that it applies vacuum to the CC motor when the RV brake lights are on, and allows air back into the CC motor to release the brakes when the RV brake lights are off.
