MONITOR
I got a replacement rear-view mirror with an inset video screen (the mirror is nearly useless anyway and it's very natural to look at the rear view mirror and see a view of what's behind you). It's sort of like link 1, except I got mine at a local Fry's and it was around $50. I was able to easily tuck the wires into the plastic trim piece next to the headliner and around to the dash area. The hardest part was figuring out how to remove the factory mirror, but youtube taught me how (turns out you just have to confidently pry/pull harder than I thought).
CAMERA/MOUNT
My license plate is mounted way on the left side and I wanted my camera to be centered. I didn't mind if it was low because I'm mostly scared of running over people or bikes and not hooking up a trailer. I wanted to avoid drilling and didn't want the camera to be very noticeable. My solution was to create a camera mounted in a hitch cover that I could remove if I wanted to use the hitch and replace or swap if I didn't like the camera.
I got a couple different cameras like link 2, all of which came with a drill bit exactly the right size for the camera. The cameras were between $9 and $19.
I got a few blank hitch covers (one for each camera) and drilled a hole in each for the camera. I trimmed the wiring so that each camera-mounted-in-a-hitch-plug had a few inches of RCA cable and connectors sticking out of them. See link 3. I now have several "plug-and-play" cameras each with different strong points (color-quality-resolution / wide-angle-ness / night-vision).
WIRING
I have a 23 foot motorhome. I bought about 35 feet of RCA cable suitable for outdoor use from Fry's, but easily found on Amazon also.
I got about 30 feet of wire conduit and something like 6 or 12 feet of wire heat shield from my local auto store (whatever was a single package). AutoZone, Pep Boys, etc. (It wasn't exotic or hard to find.)
I was able to easily find good places to zip tie the cable-in-conduit underneath the chassis all the way from the hitch to the dog house. When transitioning from sort of the outside edge to where there'd be a lot of heat (the vehicle part), I covered the cable with the heat shield. The cable and heat shield came up very easily through a gap between the doghouse and the back of the dashboard area, where the mirror cables were waiting.
For power, I spliced power from the hitch connector for the camera and there was power easily available in the dashboard area for the rear view monitor.
WIRELESS OPTION
I did buy a wireless kit from Frys and a different system from Amazon. Both had a lot of noise when I had either the engine or radio on. In both cases I attached the transmitter just behind the hitch receiver and the receiver in the hollow space next to / between the radio and glove compartment. Hardwired was noticeably better and just as easy!
I was 8.5 months pregnant! You can do it too!
Links referenced:
1) https://www.amazon.com/AUTO-VOX-Adjusting-Brightness-Rearview-Monitor/dp/B00J863EI2
2) https://www.amazon.com/Backup-Infrared-Camcorder-170-Degree-Waterproof/dp/B0160OOHQW/
3) https://www.amazon.com/Trailer-Hitch-Cover-Insert-Receivers/dp/B00SVNRJ6Q