There once was a suggestion thread about mirrored ships. Combine that idea with the idea of DLC ships and you get a Pyramidion/Squid/Galleon with the side guns on the other side, a Mobula with the ladder on the other side, a Spire with the hull and balloon components back in their original positions.
A Harpoon that actually reels in for 5 seconds, like we had before, a Harpoon that holds the target within the same distance for 10-30 seconds, similar to now, could work for DLC like guns.
Each of those things for whatever price Muse thinks is appropriate. Basically, alternative versions that offer no, or just very little, numerical advantage. Do the same for Alliance mode stuff and suddenly you can support Muse once more.
Yes, the above mentioned ideas aren't going to blow most people's mind, but for competitive players, who may care about the game the most, it may be something that can be worked with.