Specifically, what to do with captured bases. Hasn't been a problem before since usually I'd just play a defensive military role, but this time I'm playing on a much smaller map and it's starting to bug me... Am I allowed to keep them or do I have to disband them to count as an OCC?
OCC rules vary( I am aware of several variations) but bottom line is THAT you cannot keep them for any length of time. The usual best strategy is to gift them to your favorite AI. Choose someone that your usual SE choices will not peeve off. The result is usually a game-long ally that can serve as a buffer from the more hostile factions.