Making level bounds visible?

I’m trying to cut open space maps into zones and use the biggest legitimate size as possible. When i go too far out of the map, the actors generally start shaking and become unstable. I tried Advanced → Bounds, but it doesn’t show the level bounds in e.g. a box or sphere grid - meaning the zone where actors are stable. The ‘Level Bounds’ class is not editable because it says it’s inherited. How could I go about this? (Or can I use World Composition to flick space empty space maps together?)

Thanks.