https://www.youtube.com/watch?v=NplyUgp2KN0 is a video review from a guy who did this on his 500 a few years ago. He mounted his monitor higher up on the windscreen, parallel with the mirrors (see 9:20). He said this worked very well and provided a natural mirror view all the way across from mirror to monitor to mirror.
My car's headunit supports a rearview camera so I picked up a cheap Pyle setup (camera and monitor) from Woot, planning to just use the camera. Then I discovered that other style cameras might be easier to mount on my car, so I might end up not using the Pyle parts at all. I've been really tempted to put it on the bike, but haven't yet.