I bought a used "Roadmaster Evenbrake 9400 Portable Proportional RV towed Vehicle Braking System" from eBay.
Mine has 3 sensitivity settings. The recommended setting to start with is the middle range, or "Average", which is the default. Says to try it, and tweak as needed. Not found a need to do so yet.
The variable proportional braking seems to work quite well. The Jeep behaves itself back there, and I never feel that it's pushing the motorhome during various braking cycles.
Not sure what system you have...