I used to make a lot of snowmobile windshields out of poly carbonates Lexan, Uvex, etc. for our mountain climbing hot rods. Soft stuff compared to plexiglass. Snowmobile could roll over it even when it was pretty cold out (below zero) usually without damage. It would also fold out of the way and not damage the operator when the machine stopped but he didn't, haha. Poly's are soft , so they scratch more easily and would need some sort of stiffener at the top to keep from bowing back with wind pressure. My best choice would be glass and when you take it to the dirt track, remove the windshield or at least fold it down.