I bought the BC-20 camera as a package with the Garmin RV 760LMT GPS. The BC-20 is paired with a wireless receiver module mounted on the rear of the GPS display unit. It is a few millimeters thicker than the non-wireless module. This may affect your GPS mount (it did for me). The pairing also means that the BC-20 probably must be used with GPSes made by Garmin that use a similar module. It is not a stand-alone camera.
I used the Gamin BC-20 as my rear view camera on a 27-foot Class C. I mounted it inside, under the rear valence, pointing out the rear window. There was a 12V (cigarette lighter) outlet immediately below the rear window. I connected a cable with an on-off switch to the outlet and the camera at the beginning of each day we traveled. I stored the cable in the front console. I found it necessary to lash the 12V plug to the socket so that it would not bounce out while going down the road, making the camera signal come and go.
The transmitter that comes with the camera has a limited range and is direction-sensitive (it likes to point at the receiving unit). On my Class C, the signal was strong enough to go from front to back. If you mount it in a toad, you should put the transmitter high on the inside of the front windshield. Garmin sells extension cables if the distance between the camera and transmitter/power locations is more than the supplied cord length. "Your mileage may vary" applies here; I believe wireless cameras are not generally as reliable as wired cameras.
The camera is designed for a rear-view application. I cannot tell you if it can be set not to reverse the image- maybe, maybe not.
Finally, as is usual for these things, applying 12V power to the camera will "take over" the GPS display. However, it only requires a single press on the correct GPS screen icon to switch between the GPS and camera displays.
I'm happy to answer any other questions you may have.