When I ran a marine game, the Cutters provided several functions: (I gave the BnCT 3 modular cutters: one hospital, one supply, one maintenance).
I deemed that the shop modules had one "full up" shop, and 2 "tipout shops". the full-up has 14 tons of internal bay, and when expanded, the tip-outs have 8 ton work bays, one on either side, but can't be used unless tipped out (I gave the 8 ton shop a 50% volume break for being useable only when opened out and not stowed for thrust.)
The Hospital was a 2 theater (4 Td SR, x2 cost), plus 1 lab (4td), plus 5 SSR (2ea), plus 6 bunks (1 Td Ea) MASH... with 2Td of stowage; one for supplies, and one for tenting for dirtside use to provide 20 cots pre-op and post-op.
I treated modules much like the Army used the Sikorsky Sky-Crane equivalents: brought in by cutter, deposited, the expando stuff is set up (takes an hour or so), and it's used as "instant camp".
Hostile Env. Bunking module is an expando as well; the 30 SSR are folded down to coffin for transit, and then expanded on landing to provide a central bay.
Cutters deployed wiht the troops; Drop ships dropped then retreated back from dirtside.
As for maintaining SL when module-less: fabric sides, and the spar has two smaller sub-spars that get locked down to provide support.