Yea, the debris screen over at the NetReg site is the ticket to stop most of the junk.
I was pondering a way to stop the sand, and I can't take credit for this idea as I saw it at the 24 hrs LeMans race. One of the LMP1 teams had filters made up to fit in the rad ducts in a slot they molded into the body work. On a stop they'd just pull out the old screens, full of crap, and slide in new screens.
I was thinking, hummmmm, I like that idea. Why couldn't I cut up some A/C filter element & do basically the same thing? I know it would work, I just can't seem to make it a "pull out, push in" type of operation.

Tom