I use a Garmin Nuvicam and matching BC30 backup/reverse camera. I like this model because it's a GPS, dashcam and backup cam in one unit. The backup cam is wireless but the transmitter is separate from the camera itself so it can be moved closer (mine's mounted to front wall of the camper).
I have had no issues with reception but the camera is too fisheye for my tastes so it can't see very far behind you and not so good for depth perception.
I wired mine to the Reverse wire in the 7-way bundle so it switches to camera when i shift into reverse. I also ran a wire from my upfitter switch so that I can manually turn it on as well.