Ken:
I've been using EZE-Kote (EK) from Horizon Hobbies. It's a single part resin that is water based and it is fuel resistant. Odor is not an issue. Formulated for model building, it is intended for use applying fiberglass. Similar to Polycrylic but can be sanded in about 30 minutes. Sands great by the way. There are some tricks to using it. If used straight out of the bottle, the water base can warp the structure (Ask me how I know). I begin with a very thin mixture of about 15% EZE-Kote and 85% alcohol, painting both side of the part at once. As the surface builds up you can reduce the alcohol. After sealing the surface, add some Zinc Stearate and it makes a good filler. Seal after filling with a thin coat of the EK and your ready for paint. For covering open bays, I first cover just the open bays with SLC film, with about 3/4 inch border. I then cover the whole surface (wing, stab, etc.) with silkspan using the thinned EK to attach the silkspan to both the wood frame and the SLC at the same time.
Jim