OK, I have been seriously slacking on the documentation end of things, but I HAVE been working. Here is an attempt to get caught up.
As always, there are more/bigger pics on my Picasa web album.
At this point in the build, it was time to attach the tent canvas to the van roof. The GTRV design basically sandwiches the canvas against the roof with this vinyl trim. When tight, this creates a (theoretically) waterproof(ish) seal against the van, sort of like a set of shingles.
I used the salvaged vinyl strips to lay out the tent spacing and get everything lined up.
In order to avoid more holes in the vinyl and canvas, I went ahead and used the strips as drill templates too - predrilled a dozen or so holes in a time.
It was easiest to fill the strip with a line of screws, then stretch the canvas onto the screws using the existing holes, and finally drive everything tight against the van roof. This was especially important in the back corners because the tent is under extra tension from sewn-in elastic to keep things taught. I imagine when GTRV originally build these, they had a method for doing things without tension, and could just drill through the vinyl, canvas, and steel all in one go.
And voila', several hundred holes and screws later, the tent is now attached to the roof of the van, making it theoretically weather-tight. At this point, the lifting struts are not installed, the pop-top was supported by a 2x4 from inside the van while I worked.