I use Finish cure epoxy to seal the wood on quick and dirty profile finishes and it doesn't come out heavy.. Use Finish cure epoxy or sometimes called Finish resin. It starts out thin and sands much easier than regular thinned epoxy.
Mix up the Finish resin and use a throw away acid brush to coat all bare wood. You can just slop it on because once you have a good coat on everything, wipe as much as you can off with paper towels. This leaves just enough epoxy to seal the wood without adding a ton of weight.
Let the finish epoxy cure overnight then sand with 320 just enough to clean up the rough surface. Doesn't take much sanding, if you sand too much you will sand through the epoxy.
Optional step is apply one or two coats of your favorite filler, Dope, Talc, Corn Starch, whatever works for you.. Let the filler dry, sand most of it off and it's ready to paint. This won't fill all the grain but it will make it look a little better.
Assuming the wings are covered with Monokote (remember this is a quick and dirty finish) Mask off the Monokote leaving about 1/4 inch for the finish paint to overlap the edge. Use a Scotch Bright pad to rough up the Monokote before painting. Painting over the edge seals it and the Scotch Bright will make sure it sticks.
Also when you apply the Finish Epoxy, make sure you get it on the edge of the monokote. I just slop it on, then clean it off the Monokote with denatured alcohol. Also make sure your Monokote is well adhered to the wood close to all edges or your masking tape will pull it up when you remove it.
Paint with Rustoleum, trim as desired and go fly...
A little note on trimming.. Rustoleum works well for trim over Monokote just be conscious of how much you put on so it doesn't add a ton of weight. Mask off the area you want to paint. Go over it lightly with a Scotch Bright pad, clean and paint..