You've done some good planning ... hope there's a construction thread with pictures in the future.
Like hawk, I have a 96"x30"x30" tank, and would agree that 36" tall will be a challenge. Get a good cleaning magnet, but even so, you'll need to be able to reach down to the sand level for cleaning right at the sand interface (unless you go bare bottom).
I concur that your fish room will be tight, and add the following equipment thoughts: I'd recommend having a 75-100 gallon tank for quarantine purposes, as a stand-alone set-up in another room to prevent cross-water contamination. For salt making, I have two heated 50 gallon containers (20"x30"), one with RO/DI, one with mixed salt water, so I can perform automated water changes (and be able to sustain a 50 gallon change per day in the event that the bacteria in the quarantine tank crashes from medication). I wasn't able to fit these in my fish room, so one takes up a downstairs shower stall, and the other is in the furnace room ... lots of plumbing
Good luck