Mallard, I did it in my moms oven in '76
I put the plexiglass in the oven on a large bread pan and for just a little while. I then set it on top of the glass window and as I remember I used a book of matches laying on the bottom to raise it up just a little so it would be the same curvature as the glass. If you layed it right in the window it would be a tighter bend, being you are on the inside of the window. If you layed it on the outside you would have a plexiglass window with a larger curve.
I DO NOT recommed using the match book! Thinking know that was really stupid, the book MUST have been empty I just remember the book in there. It did leave a few tiny little dents in the plastic. I would use something else now. Maybe even nothing at all and see how it goes. The plexiglass is cheap so experiment. Back then, I was given a couple of sheets and I really didn't even know where to get it. Today I would go down to OSH or TAP plastics and just buy some more.