I replaced a window in my TT with a tinted acrylic. It is a lot tougher than glass, but yes, it will scratch.
I would go with Lexan. It is very tough material. I have worked with and tested Lexan for some window applications.
In one of the tests I took a fire extinguisher and slammed it into the Lexan window as hard as I could. I hit it so hard that I knocked the entire display over onto the floor.
After righting it again, the Lexan was perfectly intact and there was only a small mark on it. The stuff is amazing!
