i see nothing wrong with GMG buying a base and renting it out to other factions:
"We don't run things here, but we have the ear of those that do"; "The GMG may think that they run this place, but we're the ones who call the shots around here".
The analogue is that Texaco mines for oil in texas, and has a chain of distribution centres (gas stations) across the world. Some of these are expensive to run as the gas bought doesn't cover the ground rent, so they rent out the stores to unrelated business (grocery stores, pet stores, gun shops, etc).
