Low impact authority server

I’m looking for hints and suggestions for making a low impact dedicated authority server that operates on different assets then the clients.
I was thinking of loading a different level on the server that uses assets with very low polygon count, like only the bounding boxes, and using that for line-of-sight checks and player position acknowledgement, and then load a navmesh generated from the highpoly level.
But I can’t think of any good way of synchronizing events with navmesh updates, like when a door opens, if I’m not using dynamic navmeshes.

Anyone has some good suggestions?