What you describe sounds very cool. with the tank that high you would have plenty of room for the sump below it.
i guess i am visualizing your tank wall perpendicular to the basement wall with the last 36 inches to the corner cut out then the hole going away from the bar 24 inches with the side wall showing from that side. If that is right, how far from the basement wall would the tank hole be?
with no floor drain i would build up the floor to allow a small containment basin around the tank and mixing station. this would slope slightly to a sump with a pump in it plumbed to whatever drain you do have. in addition i would want some kind of utility sink for the water change waste, cleaning water, and the RODI waste to go into. if the wall is standard stud construction i would consider how the lights would hang and whether the part inside of the wall is shadowed. i would protect the hole in the wall from splash or other moisture and make sure it is sealed so that wall debris does not fall into the tank. the quarantine question was in reference to concerns i had read about that suggested aerosol contamination of the qt/dt/sump if the qt was closer than 6 feet from the system.
which mine is, lol. if you are going to have a DT in-wall having the wall open to the room seems counter to the presentation: noise/light/clutter.
depending on what size water changes you are considering, i would want SW storage of twice that. I have 100 gal system. i change 15 gal at a time. i have 30-32 gal drums one for FW, one for SW. I can make up 2 changes at a time, use one, and have enough spare water to do another or make adds if the salinity drops. i am going with the economy version til i see how much water i actually need. having everything in one area saves the need to hard plumb everything, yet gives me the opportunity to add sophistication at a later time as i learn. one thing you might consider is the ability to feed from the front in case you want to show someone the feeding behavior of your animals.