The best $100.00 ever spent was for an after market camera. Don't bother with a wireless one reception is bad. DH has a very hard time with left and right. So I do most of the backing. We wired the camera power to the running lights and ran the video cable down thru the ladder, under the camper with stick-on cable clips, up thru the front compartment, then thru front wall with adapter, more clips to the king pin. Cable in truck was run under the seat out the back of the truck ( two more thru wall adapters for truck body and truck bed). As long as your head lights are on the camera works. Some cameras even have sound. Ebay is the best deals on all components needed.
Now just practice.