[Spaceships] Lifesupport (or lack there of)

[Fish]

Cabin space is denser than open space, I feel; open space is just a big empty volume of air with only a limited amount of ground to stand on. I'd probably go with four bunks per cabin, at 2/3 cost — assuming the need for air pressure, minimal temperature, radiation shielding, and energy (for lights, if for nothing else) but not for water, food, or fresh air circulation.

Why air pressure? For one, to conduct sound; for two, to help dissipate and/or regulate heat from equipment and electronics.