Fiberglass usually resists almost any chemicals you can throw at it. I suggest trying to find the nastiest paint
stripper on the planet and, after trying it on a sample area, go with that. I have used some that lifts latex so totally that you can hose off the goopy mess after it cooks for about 15 minutes. But.... ya gotta be sure you get it all off, especially around the windows
and in cracks and crevices.
BTW: A frame off restoraion in a month??? You must have a big crew, a fully equipped shop and a very understanding wife. What did you have to promise her???