Fiberglass Tip Tanks Question

Got a problem here, and I'm wondering if anyone else has run into it before.

Five years ago (or so) the previous owner of our Cherokee 235 repainted the
fiberglass wingtip tanks.

Apparently he had an automotive body shop do the fiberglass work, and around
the filler necks they used a fiberglass that was NOT impervious to gasoline.
Thus, the fiberglass resin turned kinda mushy, and little chunks of it
started coming out. Paint wouldn't stick to it, and it just generally
looked like crap. Eventually it could have become an airworthiness problem,
as the filler necks might have come completely out of the fiberglass.

My A&P has now dug out all the gooey fiberglass, and replaced it with a
gasoline impervious epoxy-based filler. After sanding, it looks PERFECT,
and I have just purchased the paint ($80 a PINT for Imron now!) to paint the
tops of both tips.

Question: In another aviation forum, someone mentioned that the gasoline
vapors can actually go THROUGH fiberglass, and get at the underside of the
paint. It then works on the paint from the underside, softens it, and the
surface starts to break down.

If this is true, then what I have done will only solve the problem right
around the filler necks. Has anyone ever heard of this? Did I fix the tip
of the iceberg here? Is there a better "fix" for the problem than what
we're doing?

Thanks!
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"