Over a year later I can report the Polyseamseal is still holding on just great on my garage-kept car.

I used hot glue to attach trim around the rear window. It's complicated, very fast, did not last long, and requires a lot of cleaning of the fabric when I switched to epoxy. One-minute epoxy has worked well, but putting a little too fast (a small section is not where it should be). five-minute epoxy that I used in the rest of it worked beautifully. Be sure to use paper or tape / whatever to protect areas that do not want to cover with glue. Mini binder clips to keep things in place.