I just added the Furrion 7 inch observation camera on my (pre-wired) Montana 5er. Mine is wired into the running lights, so when truck lights are out, the camera is off. At first, I thought it would be great to have it on all the time and I could use the monitor inside the camper. But then, it would be on all the time, and after thinking about that, realized that really not a good idea. So, wired into the running lights was a good thing after all.
As stated above, check the wires at one of your clearance lights and tap into it.
The Furrion model comes is 7 inch and 4 1/2 inch. I got the 7 inch, the 4 1/2 just look way to small. The monitor plugs into a cigarette lighter style socket.
I just installed it this week, and have not had it on the road yet. Going out again Friday afternoon, so will get to use it on the road the first time then. I'm really excited about having this. After last week-end I KNEW I wanted the camera for sure.
I was backing the 5er into the campsite. I was backing over the grass, angled for the graveled pad. No trees or anything in the way. My wife (my spotter) was in the front seat of the truck. It was such an easy and obstruction free back-in, I didn't need rear end viewing assistance.
Well, I started backing in when the neighbor camper woman started yelling and screaming to the top of her lungs over and over and over again... "STOP! STOP! STOP!" I'm thinking, what in the world is going on. Is she upset because my tires are in the grass?
I asked my wife to go check behind and be my navigator. She jumped right out. Both her and the woman yelling were behind the camper. I still couldn't see what was going on. Finally, my wife appeared in the rear view mirror and motioned for me to come-on and said everything was OK. I'm a bit shaky at this point, but I do.
Once in place (which was very easy), I asked her why the woman was yelling so much. Wife said, there was a kid on a bicycle that wasn't stopping when you were backing up. She was yelling at the kid to stop. The dumb kid wasn't listening and was heading right for the back end of my camper.
An observation-back-up camera would have come in real handy right then. That was the decisive moment when I finally made up my mind I was getting the camera. Monday after work, I drove over to my local dealership-RV repair place and purchased it. Put it on that evening.