Hey James, Love your town! I bought a 1940 Chevy from a guy up there 10 years ago. If you can make good cardboard templates there are glass shops that will cut and make the tempered glass for you.
Lexan although inexpensive will scratch easily and will fracture over time with deterioration from sunlight and heat not to mention the normal body flex issues.
2 great shops-one here Santa Clarita,Ca--Preferred Glass
and another in Burbank,Ca---- Zaun Glass
I have used both of these companies to manufacture glass for a variety of cars from Model A and T Fords to yes that 40 Chevy
Being that most Jeep Glass is all Flat it should not be too hard to find a shop to make it up for you.