Yes, I used Citrustrip on the entire trailer. It did the job- more work required in some places that others. But it did not damage the fiberglass, and didn't make me want to pass out from the fumes. It also was gel-like so that it would adhere to the vertical surface quite well.
It sounds like you've found the pertinent posts, but here's the index to the whole trailer saga- which is still in progress.
My Quality Day: Index for Fiberglass Trailer Refurbish