Better yet is to make it out of Lexan. Plexi will take 17 times the impact for the same thickness as glass will. The Plexi weighs about half of glass. Plexi will break from a rock impact, however Lexan will not, it will only mark it. Lexan is usually a bit more exspensive than Plexi but well worth it.
When I was doing plastics fabrications I was asked on a couple of occasions to quote on replacing the windows
on semi rigs with Lexan when there was a truckers strike coming up.
The strikers would stand on the highway overpasses with sacks of rocks on a rope and smash them into the windows
of the truckers who wouldn't go out.