When mine arrives sometime in June I'll be putting together a custom harness with automatic camera switcher to detect when a trailer is connected and when it is not to automatically switch between the camera on the trailer and the camera in the tailgate
I tow a small trailer frequently with my Mav and would really like to add a camera to the trailer. I looked at the automatic camera switcher you referenced in your post above, but I cannot tell if it works with the factory installed touchscreen or something else. Ideally, it would just use the automatic switcher with a trailer mounted camera and display on the factory installed screen.