Topsides only needed fine sanding. Mostly sanded dry, with 220g on a block to keep everything nice and flat. A fine guide coat was sprayed over all the white areas first, so that I could see when the surface was pretty flat.
If I were going to prime, then sand, then paint, I would not have sanded to such a fine grade. However, all surfaces were in good enough condition that I decided to paint wet-on-wet. Prime, then paint straight over the top. Saves a lot of time.