The seat off the Touring will fit if the grab rail is removed. The grab rail from a touring would also bolt on, including the one with a back rest. The Touring rail with the rear rack might also work but there is a support bracket that mounts to a frame section under the fender for support. You would not be able to use that or you would have to fab a set of support brackets.
At any rate, the only thing keeping a different seat from going on it the rear grab rail. That comes off in a matter of seconds.
edit: Since Hepco Becker finally came through with bags and brackets, I'm hoping they may develop a grab rail with a back rest and some kind or rear rack. If so, I'm in. I'm pretty happy with the bags even though I would prefer hard bags.
John Henry