I have a slightly different model of the Garmin backup camera, the BC-20 and not the BC-30. I would expect that they behave about the same. I am very happy with it.
I'll explain my set up. I use it with the Nuvi 2798 (came as a set). I have the camera mounted inside the rear window of my
Scamp 16 and use the camera extension cable to run the wiring along the ceiling of the trailer to the front closet where the transmitter is attached to the inside front wall of the trailer. I wired the power into an always-on 12V circuit and added a manual switch to turn the camera off/on, since I use it as a rear view camera while driving and not just for reverse motion.
With the transmitter mounted on the surface of the rat fur it had the foil/bubble wrap insulation between the transmitter and the GPS unit, which degraded the video somewhat and the video connection would sometimes dropout (also affected by how much stuff in the back of my pickup.).
I cut a small hole in the rat fur and insulation to mount the transmitter on the inside surface of the
fiberglass and now there is no problem with the video link to GPS unit. The GPS receiver sits on the dash of my Nissan Frontier pickup, and I have a Snug-Top camper shell cover on the back of the pickup.
As I said before, I am overall very happy with the performance of the system.