I own 2 of these amazing toilets. We are moving the 2nd one from the now totally demo'd bathroom to a brand new one we are building. Clearly, we can do a 12" rough-in from the planned finished wall but I'd rather not have any more excess space behind the tank than necessary. It seems that "something" less than a full 12" rough is do-able. From what I've read on Toto's site, I can probably get away with 11 1/4", perhaps less?

While still leaving a BIT behind the tank, say 1/4-1/2" what is the REAL bare minimum that the rough-in can be placed at?