Anyone done this? I can't imagine it's too hard, but my concern would be a "reverse" reference that would activate the camera.

My plan is to do a reverse camera off a pop out screen headunit, and 2 side cameras in a rear view mirror. I'm hoping to pull a signal from the turn signal lights that will auto switch the cameras in the rear view mirror. (IE you hit the left turn signal and the left camera turns on)

I have the sponsors to pay for all this, I just need to work out the logistics