I have only seen the corner windows cut one time.The guy told me he sandblasted and wet sanded them.(yep they were real glass) He also left the back window stock and lined up the bottoms of all the windows .It looked(i will look for the pix of it) great. He said it only took him 3 windows and about 5 months of tinkering to get them done. Plex would be the way to go.
