There are still some butyrate dopes out there. The last I used were from Brodak. They are relatively easy to use but should be described as fuel resistant rather than fuel proof. If you really want to get paint that is proof against glow fuel then a catalyzed paint is the way to go. There are some water based two part paints but most use thinners and catalysts and are best applied with an airbrush. If all you are looking for is fuel proofing a firewall or similar then there is a product called Kwik Poly that is a thin brushable resin that sets up very quickly and is easily sandable. The down side to most two part paints is that they are expensive. The color scheme on several of my airplanes was determined by what left over car paint I had on hand. If you move over to gasoline engines, your options open up quite a bit. Those planes can be painted with every thing from rattle can paint to latex sealed with Minwax polyurethane.