I like to keep things simple. We have a DP with the large mud flap. I believe they work well if adjusted properly. On short weekend trips, I don't use any protection. On longer trips, my first choice is a car bra. Initially, it takes a few minutes to put on at home, but I leave it on throughout the trip. "LeBra" makes a bra (about $85-$120) for just about any car.
My second choice would be the plastic type protector that attaches to the top of the tow bar.
My third choice would be the Protect-A-Tow type that uses a horizontal blanket.
Back to my keep it simple....I like the bra because it goes on at the beginning of the trip and stays on unless I hit some really nasty weather. Then I pull it off, clean it quickly with a towel and replace. The plastic protectors require a place to store them or leave them hanging on the back of the coach and can interfere with bike racks if you use one.
The last type, "TO ME" are too much work. Many love them, but at the end of day they have to be disconnected from the car and stored, usually at the back of the coach. The problem is that they get filthy and you have to handle them. Plus they take some getting down on your knees to install/connect.
Just some things to think about when you make a choice.