I've played around with smaller pieces over the years. Even knew one guy who blow formed motorcycle cafe windscreens. He had built a homemade oven, would clamp the piece between a solid piece of plywood and one with the outline cut out, get it to just the right temperature, then blow compressed air under the plexi. Cut the bubble in half and had two windscreens. It was a bit of an art but the result was beautiful.
I've also played with Lexan, its more difficult because you have to bake it at a lower temperature for several hours first to get the moisture out. Otherwise it will bubble inside when you reach forming temp.
They guys I went to for the hatch were plastic fabricators and had temp controlled ovens, knew exactly what to do.