Covering cars when towing

We have ordered a Le Bra for our CRV. We have never used anything since our coach has rear mud flaps and a full width rear flap. All was well until we got to a road in Oregon that had just been resurfaced with tar and chip. We drove about 50 miles on it and ended up with a lot of tiny chips in the plastic below the level of the edge of the hood.

I've read the warnings about grit getting under the bra but my plan is to remove it often and clean under it. We've talked to a number of RV folks who use them and have had no issues.