I have installed wireless backup cameras on 4 different RVs that I have owned (still own 3). They do NOT require batteries (which sounds like it was your concern). Very reasonably priced and a fairly easy DIY install if you are handy.
Here are two styles I have used...
https://www.amazon.com/gp/product/B08H1WZSK9
(gets power from your license plate lightbulb)
https://www.amazon.com/gp/product/B078PDH6Z8
(gets power from your up top running lights)
(I post as examples...you can find many different companies with similar products)
You can search for different sized monitors to your liking as well. The monitor mounts wherever you want it on your dash with double sided tape and is powered by your cigarette lighter socket.
Let me know if you have any questions about install.
Happy backing up!
Chris
San Jose, CA
Own two 2015 Thor Majestic 28a Class C RVs