A suggestion... take it or leave it...
At this point, with the majority of the decks already laid in, I'd seriously consider putting some "rings" around the periphery of the deck structures you've created. The secondary hull is, after all, circular in every cross-section (albeit, I'm not 100% convinced that every circle shares the same axis... anyone able to confirm that as the case or not?).
So... putting a "shell" around these decks at this point (ideally a transparent one, or at least one that has huge holes you can see through!) seems like the obvious next step to me.
Just what I'd do... it's your project, have fun!