This was going to be dead space. I previously showed a pic where it was just framed in...now it has walls. We picture a double door, but aren't decided yet. The fiberglass tub (or whatever magic material they call it) is fully enclosed and there should not be a moisture problem up there.
We originally thought the door would be on the bedroom side of the wall, but realized we have a large piece of furniture on the bedroom side that would block access from the bedroom.