Painting with a spray can is not only acceptable but in some cases a preferred method for smaller models. Unless you can get epoxy from the auto store forget it. The best you will find as far as fuel proof paint is from a hobby supplier. If your local airport has an FBO he may have Randolph or another brand of butyrate dope which is usually exhaust fuel proof but may not hold up to direct fuel application. Even the specifically made hobby paints usully have a disclaimer that says fuel proof up to 15% nitromethane. Top flite has colors that match their Monokote. I believe Oracover does as well although I haven't tried it. Shop your LHS if you have one or go on line to any of the major suppliers.