Digital Wifi backup camera, DYI for under $60

I like this $0 solution, of course, only $0 if you have the parts already

Before buying a truck with built in camera, I kept an older gopro on a tiny tripod in the truck all the time. Just turn it on, set it under the trailer's hitch looking up and out, and then back right in. Cellphone already lives on the dash as a navigator, so it's easy to pop into the gopro app and watch the video feed.

GoPro Backup Camera

Interesting a lot cheaper than some of the cameras