Back up alarms are required on commercial vehicles by various rules (Not so much by laws) and on some equipment by OSHA rules and laws.
None of this applies to privately operated RVs.
How to install..
There are two types of back up alarms.. At one time Radio Shack sold a replacement for a commonly used back up lamp, this had a halogen lamp in an electronics socket adapter (Smaller lamp but same amount of light) the electronics were the beeper. You simply replaced your back up lamp (one of 'em) this this turkey.. ALas, they no longer sell it.
Option 2 is a larger thing with two wires.. The red one goes to the back up light POSITIVE lead, the black one to ground, and that's all folks .