Marcus,
First off, a heat gun is way too much heat unless it has multiple heat settings. In your first post above this reply, there is a metal with cardboard piece that is screwed to the sail panel. This is used to staple the headliner material in place. I see it there, but it has some black finish on it.
A bit below that, there are two, approximately 1/4" holes, about 6 inches apart. Those holes are for trim clips that are mounted to the back side of the sail panel board that has a piece of the panel cardboard glued onto the backside of the sail panel board. I hope that makes sense. Unfortunately, I am in Florida till May and everything is back in Nebraska or I would be posting pictures to help with the description.
The headliner material on the sail panel wraps around the forward edge and the back edge of the roof metal. The forward edge is glued and covered by the wind lace. This is the quarter window area I'm referring to. The back, rear window, is held with glue and covered with the plastic trim. There are molded plastic corners for the top and bottom of the rear windscreen trim. Those pieces are available along with the three plastic pieces. Unfortunately, these are only available in black, so you will have to paint them blue to go with the interior.
Oh, at the bottom of the sail panel, DO NOT wrap the material around to the back side. It lays out over the metal of the package tray metal and is covered by the package tray board. Being that your Skylark is a hardtop, the package tray board used is the woven style.
Also, there should be two plastic pieces used on the package tray board. Those are also available, but not cheap. I see that OPGI has these pieces available.
Loren