I'm planning to put an HO gauge airport "ramp" (where airplanes are parked and boarded), and needed a large hanger. Guess what? The Plasticville "O" guage hanger works well (The old "K-line" "O" hanger is better because you don't have to kitbash new entry doors for people)....
Just something to consider....
What is the O gauge hangar intended to be used for?