At the CABA meeting last night (Capital Area Beekeepers Assoc.), which is the local club in Baton Rouge LA....One of the members did a presentation showing a number of different methods for performing splits and other task. One of the things he touch on, with quite a degree of excitement was a two queen tower. For whatever it's worth, he raved about this approach like it was the best thing since sliced bread. His emphasis was really on the increased honey production, which he made sound, extremely significant.
He had pictures of a hive that had been stacked 13 boxes high, says at the time he was too busy with his full time job to yank any Supers and did it just to see what the hive could produce. It was quite a picture!
Good luck, and if you try it, let us know how it goes. :)