I might be able to raise the seat some. I have intentionally fudged a slight amount on the seat height to keep the handlebar/seat height relationship about level.
Another thought is to try and raise the saddle a bit, and then move it back (aft) a bit. The more upright you are, the more forward your pelvis position. If you raise the saddle, you'll have a little more bent over position. This will cause your balance point to move backwards, and your butt will follow. So, if you have some wiggle room, as you say, then try maxing it out.