Forming Plexiglas

[mauledriver]

I have seen a glass shop mobil service truck work with plexiglass. You've seen these trucks haul large sheets of glass, and windows on angled racks, basically
the truck had a six foot length of schedule 40 black iron pipe approximately 2 1/2" in diameter, heated internally with a propane burner, and attached to the big rack on the truck with a couple clamps, The pipe stood vertically and was not capped. The service person fired the "bbq" burner and went about other tasks, the pipe section had an oven temp gauge, nothing too fancy,
There was no contact between the pipe and the sheet plexi, he worked it back and forth across the heated pipe until the area he wanted the bend was "at the temperture" all this was done without jigs or molds. He had done this before, can't tell you the thickness, or temps. At the time I just found the process interesting with little thought of using this method until a shielding guard for a process that used water was damaged. Myself and a coworker used this method with the pipe in a vise with a heatgun blowing through, took a little longer but we made three bends to form a box to shield the escape of water.
Sounds like you are just rolling one edge? to create the leading edge of your skylight? Check with a local glass shop, they may use this method and or have scrap that you can do the tests first.

[mauledriver]

one other note, you can us clean window glass as a work surface