Adding additional cameras

I installed 2 additional cameras on my Gen 3 2012 Prius Plug in. I wanted to be able to see in front, so I wouldn't keep hitting the parking slab. It made an awful noise as the front spoiler buckled under the vehicle. I also installed one under the passenger side mirror, to see how close I was parking to the curb. There was a convenient video input jack on the back of the head unit, but it would only accept input from the cameras when the car was rolling and in reverse. So the trick was to put the car in reverse, apply the brake while the car was still rolling, and switch the inputs to the appropriate camera. That made it a bit awkward to use, but there was a commercial solution available that provided pulse code modulation to the head unit, to fool it into think the car was rolling in reverse. I never went that route, so I left it that way; still useable, but awkward. Eventually the head unit failed and had to be replaced. I suppose if I were to do it over, I'd install a separate display screen.