Just a few notes on camera systems.
Firstly wireless.
Only the older or cheaper systems suffer from interference. the latest systems use 2.4GHz digital communications with the cameras actually synced to the monitor. These cannot pick up other cameras and being digital it is all or nothing (like your TV) and, if nothing, it is usually just a matter of adjusting the antenna.
Back up v's rearview
It is important to note that a back up (reversing) camera is different to a rear view camera. Backup systems are usually interfaced with the reversing lights and provide an extremely wide angle (170deg) view with very limited depth of view. Rear view cameras on the other hand and are designed to provide continuous rear viewing while driving. These vary from 45deg to 120deg viewing angle depending on the task (back up viewing or highway viewing).
Cheers
Craig
InnoTechRV.com