I have thought of a way this could be started!
It has to be automated to a degree and totally tied to the BGS though.
Here it goes:
When a minor faction gets enough influence, just like expanding into a new station, some area of a planet in the new expansion system will be designated by the BGS. This area will act like a persistent POI in a sense.
The BGS will place a transient base here, as part of a hidden mission with a non determined time limit, which will automatically expand or shrink in relation to the influence of the minor faction it is assigned to. Players will affect it's influence by either running missions for the faction in the faction's home station or the land bound base directly, or can go against it, or attack it directly. The attacks, for instancing reasons, should be handled by the automated defenses but while hard to kill outright, the strength of the automated defenses could be tied to the influence of the minor faction.
I'll try to expand on these ideas in time, now I'm out apparently or my wife will kill me