We have geometry building block soup that is comprised of planes, boxes, non box convex hulls, and mesh colliders. All thrown together in various configurations. Colliders can come and go at runtime. it would be a lot simpler to just use mesh colliders all around. Creation performance isn't an issue as we can partition that to something manageable. I'm unsure about queries though and also memory usage. No dynamic bodies that would be interacting. Collider/ray casting against these would be fairly low.