Use brake controller to power backup camera?

I installed one also. Tried the always hot at bumper plug wiring and the power fluctuates just enough to keep shutting camera off then it had to reconnect to display and that was a pain not too mention hard on transmitter. Just went ahead and got longer cable from Garmin ran from camera to transmitter glued to pass thru window we never use and ran wires to onboard battery directly. Installed a rocker switch between to turn transmitter off preventing constant searching and battery drain when parked. Works like a champ now. Can monitor trailer towing, traffic in city or heavy traffic, or just use map, only takes two taps on the screen to change between map and camera. Display can be moved into the camper to use for security purposes at night or anytime. The transmitter WILL run down batteries if not switched or left in on position. I got a lighted one so I can't miss it.