I once made a miniature fire station for my Hot Wheels / Matchbox size fire trucks. It was card board as well. I made it a two story for two reasons. One was so I could put in a traditional brass fireman's pole made out of heavy guage brass electrical wire. The second reason was so I could keep the truck bay doors solid because I wanted windows in them. They tracked similar to your design, but they went up inside a pocket wall in the second story. I used sewing thread attached to the corners of each door routed to the back of the station house so I could operate the bay doors. The upstairs had a few rooms for a sleeping area, kitchen, etc. I also added HO scale train lights to the rooms and the truck bays downstairs.
