So, GPVS, General Purpose Vessel Systems, is something somebody wants?
I did just that thing back in O2003 days, newer released.
Expected feature list anyone?
You link in the dll, define volumes, define electric generators and consumption, define O2, pressurisation, etc, etc. Just like UMMU.
For short trips, like 2 week orbit, it should have lithium based CO2 absorbers, but for longer trips and bigger vessels, you may need a greenhouse with trees.
Things that could get your crew killed:
-Pressure problems
-O2/CO2 concentration problems
-Starvation, dehydratation
-Temperature
-Presence of toxic substances (waste or vessel systems substances)
-Lack of air conditioning/filtering would release floating human particles that might not kill but could harm people.
-Other?
If you are going to work with vessel supplies, you might need chemical reactions and stoichiometry.
A green process works as follows.
CO2 -> plants (trees are more efficient) -> O2 - > Humans -> CO2
Food -> Humans -> Solid waste -> Bioreactor -> Compost -> Plants -> Food
Notice that food contains some water too. And that's what makes calculations a bit complex, as well as biochemistry of humans and plants, to calculate proportions.
Water -> Humans -> Wet waste -> Bioreactor -> Water + Urea (useful for compost or for industrial use)
A craft has basically 2 systems:
-Hydraulics
-Electric systems
Subdivide those systems and you have a good vessel.