Not the answer you're probably looking for, but I did a hardwired camera for the rear only with a dedicated 7" screen, and it's always on when we're moving.
The reason for hard-wire was that with the last wireless I tried, I'd occasionally see someone passing my side window about the same time they were showing up at my rear bumper on the camera due to the latency between the camera and receiver... With the wired connection, I know it's realtime.
I'm of the opinion my side mirrors work well enough that I don't know what I'd gain from having the side cameras.
- 2019 Grand Design 29TBS (had a Winnebago and 3x Jayco owner)
- 2016 F-150 3.5L MaxTow (had Ram 2500 CTD, Dodge Durango)
- 130W solar and 2005 Honda EU2000i twins that just won't quit