Rear View Camera

Somewhere, either on the display unit or the camera itself, there's a connection to the reverse circuit to activate and deactivate the camera. If you connect that instead to a constant-on circuit (or, more usefully, one that's on when the key is in run), the camera will operate all the time. There's no need for an additional camera. If you want to get really fancy, you could install a switch to select between always on and on only in reverse--which would obviously be a bit more straightforward to do usefully if the requisite connection is on the display unit.