You can do that, but it will add significant weight. Warbirds already have a high wing loading usually, so you may not be happy with the way it flies once you're done. Stopping short of stripping the whole thing down and starting over, why not try sanding or scraping the lacquer off where the problem is, then clear coating the whole plane with something that is truly fuel proof? An automotive clear coat that has a hardener added will work, as will the Klass Kote mentioned above if you need to brush it. If you do have to totally repaint, you'll wind up with a much nicer flying plane if you go ahead and remove the existing paint. It may be less work though to just take off the covering and start over from scratch.