Adding a running costs to active ships while inactive ships can be mothballed through not giving them consumables.
Idea: Ships have a set amount of crew and this crew needs food, water and clothing in the form of “crew consumable bundles” made in PAC with DW, RAT and OVE. The ships have a CoGC like (bi-)weekly upkeep (this cycle + buffer for next cycle) where bundles get automatically pulled into the ship buffer (if activated) to not introduce additional micro aside from “having some on your logistics hub(s)”.
The added costs woudn’t be high and the ships would only accept the bundles meaning that PAC would get something to do. Ships without consumables fly only at half the speed.
Further ideas: advanced crew consumables for advanced engines / reactors as these ships do more trips per cycle so the cost per cycle could be increased slightly (+ it adds to the fluff of the game)