Protection for our tow dinghy

I find this thread very interesting. A couple of questions come to mind. First I do not doubt there is a problem as stated earlier, my question is how and why does this happen? Is it a vacuum created behind the stiff rubber mat at the rear that then sucks stuff up? If so, would a heavy duty porus material solve it. I wonder why the industry has not solved this issue, I see many, many RV's with mats across the rear. Would the "broom" type some have fix the problem? What about a verticle gap in the middle of the existing rubber mat? For now it appears to me that the protect-a-tow mentioned above is the easiest solution. Any comments?