You mentioned six Ship Troops/bodyguards. May I suggest that their space can be reorganized with double occupancy cabins, with the 6 dton "liberated" used as their training area/dojo. That will be a 4.5x6m (15x20') room, probably a 15x15 foot hand-to-hand mat combined with a virtual firing range. The 4.5x1.5m (15x5') strip down one wall behind a wall of net holds a treadmill, weightmachine, and a locker for pads and practice weapons. You could steal a little from their common area tonnage, too, add another excersise machine and maybe a 'fresher.
No extra tons or cost, since this is part of their normal living/working space, unless you feel generous
