I had a co-worker order me one of the Wolfbox units from Amazon for my Suburban - I don't have the model # in front of me but if you google "Wolfbox Mirror" (without the quotes) you will see a selection of them. I have the barn doors with small windows and dark tint, so rear visibility was effectively none.
I mounted the rear cam inside the passenger side rear door at the top of the window, pointing mostly downward because what I really want the best vision on is anything close enough to be a problem. The provided cord was actually long enough to go up under the plastic interior trim all the way from the back door to the windscreen and plug into the mirror assembly without problems. I also got the optional GPS puck so the mirror will display/record speed and direction as well, since my front panel speedo reads more than 5MPH off.
It works perfectly by day, but unfortunately at night that dark tint in the rear window makes the reverse-view cam less useful. Removing a small circle of the tint to give the camera an unimpeded view would help but I havn't done so yet. Obviously mounting the camera outside would be even better. They claim it is sealed enough to do outside mounting, but I decided I prefer it in a more protected spot.
I did not bother hooking up the reverse light interconnect to force the head unit into rear-only view automatically because the camera resolutions are good enough that I just leave it in side-by-side view mode full time. The head unit records both cameras, sound from the front facing mirror cam (and the GPS speed/direction) in 2 minute clips onto a microSD card, rotating off the oldest files to make room as needed. Video quality is quite good.
The head unit just attaches over the factory mirror with silicon stretch straps, so installing and removing the head unit is simple. It gets power from the normal 12V lighter output - they sell a kit for wiring it in to auto-powerup when the key is switched on, but it would be pretty easy to set that up yourself if you are moderately comfortable with automotive wiring. I have had it for a couple years and I'd buy it again (and if I can sweet talk someone into ordering me another one I will because I'd like to have one in my car also).
