Ive read alot of aro keepers like cubes instead of your standard tanks. A person i know mentioned he had a shallow cube for his aro who was well over the 2 foot mark (cant remember how long, just remember thinking that was way bigger than everyone says to account for size wise), held around 2000L though i think.
IMO if your gonna get such a fish do it properly, no skimping on tank size. Just cause it can turn around in a tank when its nose and tail can touch either side doesnt mean thats fair, you wouldnt put a dog in a pen that was only just wide enough for it to turn in would you?
Good luck