I just got a huge sheet of the think lexan. Im going to rebuild my back hatch with fiberglass and lexan. I will tell you how it comes out. Fiberglassing starts tomorrow. Lexan will work, it is bendable and if you can squeeze it into where you want it and glue it, it will stay.
I wouldnt try the oven thing, Anything over 600 degrees and it will catch on fire.
yea Dogstar I agree, The back hatch doesnt really need any curvature at all. It can be flat. But if you cut the plexi a bit larger than the diameter of the hole, The plexi will bend upwards to fit. Any then you have a nice small curved bubble on your car.