FireWall
I still use epoxy but thin it with 99% pure rubbing alcohol - about 25-30% alcohol. Still seems to work the best.
Fuel proof dope will work as well and you can get a fairly good colour match with your covering colour.
Another thing I've tried is varathane, not the Diamond as it's not fuel proof. Seems to work not too bad but I have found if you get a scratch in it down to the wood the the fuel will work under it and lift it.
CA has been used but I have seen fuel soaked fire wall that have been soaked with CA to fuel proof the firewall.