Plus, I'm pretty sure the Fantasmic staging area is only for the barges and not for the performers, correct?
Speculation from my rebel spies is that the new Marina building may include costume storage moved from the main entertainment building behind Toontown. This would mean that only those costumes going out for cleaning would be transported back every day. Some costume components are only cleaned every second or third day (I'm told they are generally not next to the performer's skin or prone to absorbing sweat). Formerly, all those costume pieces were going back and forth every day. But I emphasize, this is pure speculation and no Bothan spies even broke a sweat.