On some Mainship MKI, I believe the first couple years had a double berth was offset to one side and a second single bunk was above it going down the other side of the hull. I can't find a picture of one right now and I've never seen one in person. It creates a one sided "walk around" of sorts, the sleeper on the outboard side would have to climb in first or the inboard sleeper would have to get up to let them out.
There have been a early mainship owners who have reconfigured the cabin pretty radically, one posted pictures pretty recently on the mainship facebook group. Looked like a ton of work and I don't know if I would like it personnaly. I think they moved the galley up to the salon area and stretched the stateroom aft, even with this, the head would limit how far you could extend aft.
The newer boats that are much wider relative to the length are really at an advantage for an "island berth", then again the difference in cost is about $100k so I can live with the v-berth. Another possibility may be finding a pullout for the salon that you could live with. Remaking the bed can get tedious, but some are easier to use than others. I have been on the lookout for a better solution to our futon.