All you need to do is put in one normal 12v relay.
The connections are:
85 negative
86 12v + that gets hot when you flip a switch
87 12v +
87a 12v + that gets hot when you put it in reverse
30 goes to the 12v + of the screen (normally 87a and 30 would be the same wire connected together)
Under normal circumstances the reverse light will turn on the screen. If you want to see it while driving, flip the switch and it will come on but not backfeed to the reverse lights.
It works like a charm, I have it wired up this way. I have the same camera but with the little screen that attaches to the windshield. The switch and relay is inside the overhead console. No problem.