Did a search and came up with a couple mentions of rotomolded wing tanks. The wingtanks.com solution is not a viable option. Press in fittings and reduced volume is a non starter.
The fiberglass/ethanol issue affects boats and motorcycles as well and it looks like the boat folks have moved to rotomolding.
I believe the Sonex uses a rotomolded tank, so why not the Kitfox? There's a rotomolder here in Indy and I was thinking about seeing what they could do.
Anyone interested?