The basic advice to balloonists, and their crews, who get a bit closer to
very big naked flames than most other pilots
, is to stick to natural fabrics as much as possible. As has been said already, nylon, and other man-made fabric, don't just burn, they melt onto your skin, which is seriously bad news
Wear nomex, or at least leather gloves, so that you stand some chance of reaching towards the fuel shutoff in the event of a fire, and keep your arms and legs covered, again for protection in the event of a fuel leak -- propane squirts all over the place (no shorts and tee-shirts, even on a hot summer's day
) Possibly a bit excessive for fixed-wing, but the principles will apply...
[Edited to add... ] many balloonists wear flight suits for much the same reasons...