Maybe we should be able to create outposts? Could be limited to 0 planets with resources nearby (to avoid having them at every 0 planet after a while)
They could act like starbases, with some extra funtion to make them worthwile. Just an idea
Instead of another complicated starbase system I would rather see a simple mechanic as the asteroid belts. Invest x Gold and you get y revenue after z turns depending on the distance to the next planet.
Not all class0 worlds could be usable in the beginning, though. Maybe gas giants do not or only if you have a trait or a certain tech. (or whatever) The revenue and type of base you put on the 0-planet could be bound to tech research.
Such a simple system should be not that a problem provided there is the dev will to do it.