The key to remember is once the towed vehicle brakes are activated, whether by the RV brakes or engine braking, the towed vehicle slows down, and once it's slowed down to the same speed as the RV, which would be a matter of splits seconds, the towed vehicles brakes release and are no longer activated. The matter of the towed vehicles brakes activating is not a bad thing in my opinion. That's why I have a brake system hooked up to our towed vehicle in the first place, so the brakes will activate and slow the towed vehicle down and not have to depend on our RV's brakes to do all the work. Having a gas RV I realize I don't have as much engine braking capability as a diesel. But be that as it may, I've yet to see my towed vehicle brake light indicator come on when I've gone down some very long and some very steep grades using our engine braking.
Steve & Nancy
2005 Itasca Sunrise 33', W20 Chassis, Ultrapower, Henderson Trac Bar
2012 Chevy Captiva Sport AWD, ReadyBrute Elite Tow Bar, Blue Ox Base Plate, Protect-A-Tow