Sand and paint can be viable depending on your objectives. It won't last as long nor look as good as a strip and paint. I did it to my Navion to provide an interim paint scheme and buy myself some time to get my RV-6 finished. I can't stand to be without a flyable airplane. I only expect a few years from mine. It looks far better than before but it's a 30 foot paint job done in stages, by me, in my hangar. It serves my purpose. If you have evidence of filliform corrosion under the paint you really need to strip it to fix it. If you do and haven't purchased you may want to pass. As mentioned, be very careful sanding or Scotchbrighting around the rivets. Preparation of the surface will control the quality and longevity of your paint job. It's harder to get everything clean when sanding so edges and rivets will start to flake earlier than when stripped.