I made a diy version of the "protect a tow", you can find instructions on line. What a waste of time and money. It was much too flimsy. It went in the trash with zero miles on it.
We also tried a hard rubber flap at the back of the motor home. It was too low and did major damage to the Jeep. I still like this option, but you have to keep it way up off the road.
We applied some clear, spray-on film on the fenders. It seams to work, but it is a pain to remove and left on is not much better than looking at a few stone chips.
When we know the roadsare going to be bad, we use a bra. It's a pain trying to keep dirt away from the paint, and you cannot leave it on (scratches), but you sometimes have to choose one damage over another.