They won't complain about the square footage — as long as you cuddle them, of course.
Though the Australian Terrier is very energetic, they don't necessarily need a ton of space to release that energy. They do fine in small spaces as long as they get plenty of exercise, according to the American Kennel Club. They need regular playtime inside or outside, though the AKC notes that if it's outside, they should be on a leash or in a fenced-in yard. They were bred to hunt rodents, so they might run off if a critter catches their eye.