3 tons hydroponics bay/lounge, 6 person capacity (no rules for this - I used GT modular cutter as basis)
Contemplating and designing long-duration cruises and vessels from time to time myself, I have always felt that GURPS was a little generous with this number, so I have a couple of notes.
1. This here above is
only for hydroponics, which means a dedicated greenhouse for growing plant-based foodstuffs and maybe recycling some carbon dioxide. It does not seem to include things like carbon-nitrogen-phosphates-etc and water recovery from sewage processing, nor does it provide a mechanism to regulate how much atmosphere is processed. Borrowing from GURPS: Space, mid-high-tech
Full Life Support would take 2dt per person and require annual replenishment and servicing.
Total Life Support as a high-tech, sealed, maintenance-free system would take 4dt per person (this effectively means going to 8dt single-occupancy staterooms). This level of complete support also tends to require a fair amount of power input and a computer/robot/crewman to monitor it. I have seen this described as being too "fiddly" to be as efficient as desired.
2. Given that your operational duration is ~8 months and you are CT-inspired, I would suggest as an alternative that you borrow a page from the
Beltstrike module and just lay in 3dt of long-term life support supplies. It means canned goods, bottled water, and tanks of oxygen instead of fresh fruits and vegetables every day, but 3dt would only set you back KCr450 and would provide ~9 person-years worth of food, water, and atmo without having to hire a gardner or run grow lights off the powerplant constantly. You have to return to a starport or spaceport eventually for fuel; you might as well stock up on groceries while you are there (and frankly, 2dt/6py @ KCr300 would probably be sufficient for what you are doing with this design, freeing up 1dt for other purposes). For color, I refer to the dedicated storage space as "The Ship's Pantry" as it is not part of The Ship's Locker. YMMVIYTU, of course.