Drats! I've already installed (quite solidly) a 1-inch white PVC pipe
(thinwall pressure pipe, from Lowes) in each of my wings, for
electrical conduit thru the wet wings. Before doing so, I let a small
piece of it soak in fuel for several days, and at the end it seemed
completely unaffected. But several days isn't the same as several
years of course...

Well, I guess my plan now will be to carefully and completely coat the
PVC tubing with ProSeal when I seal my tanks, as an added barrier to
any possible reaction.

Greg Reid