Hello Joe, *lol* on the beer.
Yes I am doing this mod, it's pretty easy if you already have the cam, or the cam and Nav radio. You wouldn't really need a Nav radio, because the mirror just takes an RCA cable for video input. It seems that the gentex mirrors were very common on pretty much all GM vehicles, so there are plenty of them (used) around. You can get a "grade A" one, working with warranty for approx $100. (and probably less than that, but I like it when a seller can help you with an install, which costs a few more $$$ when buying it)
My 2013 SSV actually is wired for it already, similar to the DIC panel, the "Onstar mirror" was not installed to make the vehicle less expensive (a brand new GM OEM Onstar mirror is somewhere around $500-$700).
So the wiring is there, the plug/harness is lying on the trim right next to the front overhead console. What is missing is the RCA cable, but you can get one, with the right leads that connect to the plug for about $15.
You either connect the camera RCA cable to it, or if you already have the camera hooked up to the NAV radio, use a Y splitter to hook it up.
I don't see why another camera would not work, unless it has a weird resolution. (I believe, not sure, but the mirror LCD is 800x600). I use the "stock" camera, or to be more precise, the GM OEM after factory/market camera. It is the same camera, just different wiring harness that comes with it. Factory the camera is plugged into the harness in the tail gate, after "market" the OEM camera harness (power and video) needs to be routed to the front, from the back, tailgate. (some hook power up to the backup lights, but that causes the screen to go black for a few seconds when changing to/from reverse to anything. Also, when changing gears from Park to Drive, the shifter goes through Reverse, the backuplights will flash briefly, meaning your camera gets "jolted" a bit, which is not a good thing for electronics in general)
Anyway, I think the mirror install is pretty easy if you already have a camera and NAV radio installed, that's one reason why I did it too, it's easy, not that expensive and ... just because I can. The other reason is, the "GM Onstar Mirror" also has an automatic dimming feature, which I really like, all my other cars (except the 79 CJ5) had it, and I miss it ... someone coming from behind with their brights on is annoying.
The 'stock' OEM camera indeed comes with a bracket, factory it is "sonic welded" into the rear applique, However I cut the hole in the Applique, cut of the "weld posts" and put it in with a few blobs of JB weld. (which is better than regular epoxy). The camera is held in place with two screws and a plastic shim/spacer, so it cam be removed.
The model number of the mirror is a "Gentex 657" 'style' mirror. GM had so many of them, that they used several GM part numbers. GNTX-657 GM part #: 25794381 / 20945097 / 22915244
and there are probably more part numbers for the same thing, but different revisions
So... Detroit ay? I was there many years ago a few times, What's with all the OSB there?
Ron