I'm looking at a TadiBrothers.com system that has hardwired cameras, split screen monitor that will show up to four cameras.
For the RV, it might be nice to be able to run the wire next to the 5th wiring plug, have a plug in there, and then hard wire to the monitor. Then everything is powered, and no loss of picture or quality due to the interference between the camera and the monitor.
I'm actually looking at it now for my Bobcat skid steer grader attachment. Mine is a Mini Might Patrol that has its own "cab" up in front of the loader. But I still can't see the corners of the blade...so I dig a trench figuring out where I am. So with two cameras, one looking at each end corner of the blade...and a 10" split screen monitor where I can see it...I can get a perfect start each pass.