I've towed one & two AI's over 8000 miles in the past three summers. I have not had a single bit of road debris damage to either boat. Most of my towing has been highway, so I haven't had to deal with significant gavel. Unless you want to count the Pennsylvania Turnpike, that is. I am towing behind a MINI Cooper, a Ford F-250 4x4 pickup, and a Ford Excursion 4x4. The trailer is a Trailex SUT-250-M2. This trailer does have the boats positioned fairly high, so that may help. As seen in the photo, I have a couple of tool boxes now mounted below the boats, but those were not there for the first 4000 miles.
Hope this info helps answer your question.
- Jim L