IMHO there are two better solutions. Mud flaps as close to the rear wheels as possible. Second, Protect-A-Tow under the tow bar. A total rear flap can cause a vacuum and actually cause stuff to fly up onto the toad. We had a full rear flap. I took it off and made mud flaps out of it and used the mounting bar to make a frame to hold the mud flaps with.
As double protection we also use the above mentioned Protect-A-Tow. It is very easy to attach and works a treat.