I discussed the rust-on-keel-issue with an expert for antifouling and anticorrosion today. He is selling the stuff for underwater protection in Germany since decades (antifouling shop). His statement: The steel of all Bavaria and Beneteau keels is of a very poor quality. There are definitly patches of "strange" material included, which attract humidity, no matter if you have epoxy or other stuff between the steel and the water. He recommended to use a Chlorkautschuk-Primer on the rust patches and to apply antifouling on it. He also said, you have to renew that every three years, and if there is some unevenness: just ignore that and sleep well. I will do so. So for me: no sanding, no epoxy.