Just as an aside, one time I had a customer who put some equipment up on a mezzanine. The only access was a panel in the wall of an adjacent bathroom, unless you threw a rope over the railing and crawled up the rope. Would this be considered immediately accessible? The panel was maybe 2 ft square.it didn't have hinges on it so it wasn't a door but it had some kind of a springy thing to keep it in place so it could be removed without tools.
there was a ladder on the mezzanine that went up to some kind of a hatch in the roof too. You might have been able to climb up a ladder on the outside walk across the roof and come in the hatch.