I've got 4 cameras in my Class A. One on each side looking at blind spots, one rear looking just below the rear window.
I live in CA and there is a (silly) provision in DMV that doesn't allow monitors to be visible from the driver's side while the vehicle is in motion. It did not mention vehicle movement when backing up. So, your guess is as good as mine.
The fourth camera is mounted (partially) hidden just behind the awning strut. It is looking at the side door, that is interlocked with an annunciator that detects anyone (or any movement) at the doorstep.
I have three monitors which can be controlled independently.
My setup maybe an overkill but the backup camera is good to have. You can buy those wireless models or the ones that operate on bluetooth.
Because of interference (RFI) and vulnerability of wireless, especially when driving with other motorists who have wireless toys, a jumble radio signal is mind boggling , I prefer the hard wire model because of its high reliability and good image display.
And uh, did I mention I also have proximity sensors mounted just below the bumper where we keep the sewer hose?
This is a feature common in high end cars.
Good Luck