My coach has the Voyager monitor. Each camera has a 'trigger' power wire going to each one that turn on that camera (thus activating it on the monitor). It was pretty straight forward to determine which wires they were. I installed a DPDT (double pole, double throw) switch to turn off the right and left cameras.
When passing somebody; I found it very annoying that when I turned on the camera to indicate I was turning back into the lane, that my field of vision to the rear disappeared. That is how I can tell I am clear with the toad!
With the switch, I can still turn on the cameras if I need them while backing or navigating in tight areas.
I found the information here Diplomat Mods