Tom P:
I remember that P.B. Dye added the front bunker on 13 when we worked on the course c. 1985, but it was steep enough that I can't remember if there was fairway in that space then.
P.B. Did have a redesign for the 18th hole with a new tee behind 17 green, which we actually started to build, before the powers that be told us to cease and desist since we had never mentioned the idea to the committee. P.B.'s dad told me before we started there that if I messed up, I would never be able to get a bank loan for the rest of my life (!), so we stopped. That was just Pete's way of telling me who I was dealing with ... although having Mr. Merrill as green chairman made it pretty obvious anyway.
I agree with you that the idea described was likely never done, since the 18th green has been up on that hill since the oldest aerial photos from 1926 at least.