Just a quick update. As a test I re-masked around the hatch, taking care that everything was sealed very well, and it was bone dry through several heavy rain storms. So I spent the last couple days picking the old caulk out from around the LP tank pan (using utility knives, putty knives, multi-tool scraper, various solvents -- whatever worked). Today I filled up the void with a nice large bead of 3M 4000UV. It will be several days before our next rain event, but since the masking tape worked and the pan itself looks to be water tight, I expect that this leak is history. I'll try to get pics someday. It the leak isn't fixed, I'll be back for advice on what to try next.
