Navmesh to Teleporting area - Workflow?

Hi Allz,

I imported a scanned room with textures into unity. I used the obj file of the Model to create a navmesh, which worked pretty well. My Problem now is, I have a huge Plane to which I attached the TeleportingScript. (But the Teleporting area ist much bigger then the actual Building/Model.
In general it works, I can teleport and navigate to my whole building and the navmesh is stopping me from the walls. But I can see through the walls the teleporting area (which is outside of the building).

So my idea is, to use the navmesh as teleporting area. Is there a way to do that? For example extract/export it and then later on import it as "Plane/Shape" and use it as teleporting area?"
Maybee there is a more efficient way, any ideas?

Thank you for you support,
Greetz