I'm reading over it.
I certainly like the idea, but their implementation feels half-baked and way too conservative. There should be options for the bastion to be available at 3rd level, if not 1st - or to be "owned" by a patron but used by the PCs.
For a fantasy game, a lot of the options feel too mundane (need more fantastical beasts available in the menagerie, need options for fantastic creatures to be stabled out of the gate if you have the funds/level - like pegusi, griffons, dragonnels and the like). Some of the options become available at silly levels - A pub at 13th level? No thought on mobile bastions of the like of ships (sea, sky or spelljamming!), Howl's moving castle/Baba Yaga's hut, cloud castles and the like.
I really don't like tracking BP points. It would, in my opinion, be a lot better if there were just base actions that you could enhance by spending GP or combining two or more actions.
I'd like to see more revisions to shore up the mechanics, but this really feels like an incomplete first draft.