I used plexiglas for a windshield on a tractor. I built the frame, then bolted the plexiglas to the frame. This is fine as long as the temperature is reasonably close to the temperature at which you mount the window. As soon as it gets much warmer, or colder, the plexiglas does some serious volume changing, which causes it to stress against the bolts. After that, it cracks.
I am designing my next Prowler windshield around 1/4" plexiglas. I am looking at over-sizing the holes, and using as few bolts as possible, to counteract the stress cracking. Will report after it is built and run a while.
Bob