The only way I could get away with not having a fish room was to have the cabinet space to the sides of the tank. The rough square footage of "floor" space for equipment is something like 20 sq ft. I've actually got plenty of space and use the area to the left of the tank for mostly storage.
My RO/DI unit and freshwater reservoir however are in my pantry.
Here are a couple more pics...I actually meant to post these before but forgot...
