The main limitation for these things is ship AI. For mines, a combination of "the station can't run away" and "mines map fairly well to missiles, which the AI knows about" make it work.
One thing I'd love to add is huge asteroids. It feels possible to repurpose some AI behaviors to handle them decently, and they're not explicitly deadly, so there wouldn't be the same "run away forever" concerns. Still, not sure if I'll end up having time for that at any point. I would love to have that in-game, though - provided it worked out well, anyway.
(A directional star corona with shadows from asteroids is right out, though, I'm afraid, as cool as that sounds. It checks all the boxes you don't want checked.)