forbidding followers from an area?

[puppy14]

I'm so very close on completing my mod, and I have a question about followers.

 

Say I have a two part mod, where in the first half, you enter a "dream" phase with jumps, twisted hallways, and weird elements strewn about. I don't want the player to bring his followers, so is there a place to "store" them while they run around? Or maybe not let them in at all with a follower?

 

There aren't any combat scenarios in these phases, so maybe just leave out the navmesh and the followers will fall through/not follow?

Thanks.