I don't think the setback seatpost is an option, due to the fact that we have to BURY the entire seat post inside the seat tube... but if I get a one-bolt post, I might be able to move it back another centimeter and a half if the bracket is behind the post.

Also, if you look at the middle picture, her hands are on the corners, not the hoods, and her elbows are almost locked. She's a little more upright than I like to ride, but even so... if I move the seat back, I'm thinking I'm going to have to also find an extremely short and extremely high-rising 1" quill stem or of course the adapter + stem route.

Any thoughts on that?