The rear fender has been repaired in the past. Welds look decent enough.
When I had at cleaning up the tail it turned out to be better than at first glance. I didn't wash the bike before the teardown, so there was a good bit of mud that came right off when I wirebrushed it and that, plus half an hour of sanding made it pretty clean.
In the next pic you can see the spot inside the body where water got in and caused the pinhole I JB welded earlier. I opened it up, cleaned it out, packed it with grease and sealed it up. Not the best way, but should hold it for now.
Tomorrow I will look after the front section of the underbelly and inside the frame where the tank will sit. Then underseal the rear fender to prevent future corrosion.