Caverun, Hunter always grounded the mast foot or as some said deck mast plate to the keel. Different on the water ballast. DougJ, The routing of the 12-3 (positive, ground and neutral) is it good that the black corrugated piping was added for protection, the one concern with it in the way of the cushion moving about would worry me. I use to use the same black piping or plume as we in the industry called it would run it below the rear berth thru the hole in the rear bulkhead and over toward the starboard side secured in place by 5200 and then thru a cut hole going underneath the galley. Everywhere there was any hole, plume was added so it would encase the edges of the holes. Like you I added the gfi to the first outlet at the galley area.
I put my breaker on the back side of the galley which was much easier to get to but added a back cover to it under the galley for safety.