I have had decent luck with this -
https://www.amazon.com/dp/B07GVHJQYK...d_asin_title_8
It's cheap Chinese wireless and works fine in my 26' Motorhome.
It also has a recorder if you put in an SD card.
For $100 it's hard to go to wrong...
I wired the camera into the running lights and stuffed the antana behind the running lights (2006 FR Lexington 255DS).
I wired the monitor to a fuse that comes on with the ignition and ran the wires along the windshield trim to above the rearview mirrior.
3 years in and it works.