tons of camera systems are out there you can spend over $1000 for the best
no matter what make sure you get "mirror immage"
so when a car is passing you it appears on the same side of the monitor as it would on a mirror.
I run my camera all the time when towing
if you want to to lowest cost get B&W
but I chose color my sytem is an inexpensive camera
and a lcd monitor I got from ebay
the only issue with this camera is the cord is too short for my 335rlbs so I used a standard (RCA ) video cable from Radio shack to get the signal up to the dash of the car