To specifically answer your second question, "would it help?" though, yes. I'd advise that any R/C plane with an IC engine (whether it's glow, diesel, or gas) should have the fuel tank compartment fuel proofed. The design of a Stik resists frontal impact with compressive forces -- for which the additional epoxy won't help much, but if the joints aren't perfect, it will make the whole thing a bit stronger in some ways.

For another application option, some of the home improvement stores around here have taken to carrying sprat-on epoxy paints. They go on real easily and seem to fuel-proof things just fine.