[a8ksh4]

Yah, the outside was fiberglassed before removing most of the supports.

Here's the revised process I think I'd follow, now, to get the best results (with or without cad drawings to work out dimensions of stuff).

1 - Attach a wood strip to the top of the cab and bend it down to the height at teh end of the tailgate recommended by the aero template. Take a photo to compare against the template, and make any adjustments needed. Record the height of the wood strip above the bed at regular intervals or wherever you want to put supports/x-sections. Maybe subtract 1/4" from the height to allow for height from layers of fiberglass and any gasket material that's used where it mates w/ the bed.
2 - Start construction by building the base of the shell that mates up with the bed. Use wood or whatever to make the lip that sits inside and add supports to keep it square and give you something to secure your supports/x-sections to during construction.
3 - Trace the shape of the cab and use it as a template to draw/cut each support at the height that was measured from the wood strip. Because the supports keep getting shorter, the template has to be moved side to side to make it as wide as the bed. Just use it to make consistent curves all the way back.
4 - Attach the supports to the base that you built and add bracing to them to keep them in position.
5 - Get creative and attach the foam to the sides and top. If you have a good table saw, it might be easy for you to cut kerfs in the foamboard to wrap around the corners, or you can do like I did and build up each corner and then sand down into multiple layers of foam to get the correct curve.
6 - Embed any wood supports where you want to mount external stuff - hinges, etc.
7 - Clean everything up and fiberglass the outside, front, and back. Then Gut the whole thing, embed any interior wood supports, and fiberglass the inside. You might choose to only remove supports/x-sections from the inside as you work your way up the length of the shell laying fiberglass a strip at a time.
8 - Go back and cut window openings. Use a razor blade to trim the fiberglass back 3/4 inch from the window opening on the outside to give room to sand a shelf to set the lexan into. Cut back a bit further on the inside to give room to round the transition to the window opening.