The Lustercoat, minwax, polycrylic, dope, etc. do a good job of fuel proofing IF you don't use high nitro content fuel like 20% . Then they turn to a soft goo and take forever to harden up again. I use Nelson's water based. Fuel proof to 100% or close to it. but Imron (auto paint) will also fuel proof to 100% nitro. Klass coat is another good fuel proof paint.

I also use the Nelson paint to seal Ultracote seams so they don't pull up. I wipe the Ultracote down with acetone. Then spray on 3M #6065 art mount adhesive. Then Nelsons satin clear. Holds great, keeps everything down tight. I also like the duller finish on most of my planes.