Following a couple of damp days, it was finally time to glue the top to the van today.
Goopy, nasty stuff, and the combination of a limited window before the glue starts to cure and a crappy caulk gun made for a pretty stressful afternoon, but I think everything worked out okay. The top is on the van now and tightly strapped into place while the glue cures. Another day or so, and I'll find out how I did.
Speaking of windows, astute readers may have noticed above that there's still one more to install. Unfortunately, I recently discovered that I was mistakenly given two windows for the same side of the van, so that part of the project is on hold until I can get a replacement. Plenty to do in the meantime though, so it won't hold me up.