I have the same issue with the Superior. I'm doing a century (tomorrow!) and definitely need two bottles. I'm not crazy about bar mount bottles and I use the seat tube for mounting a pump, so I was able to find an option that mounts to the seatpost. This works in my situation because my fit has a lot of post to work with. Might work with less post if you use a regular bottle.
The bottle tucks in nice under the saddle and doesn't interfere with my pedal stoke or the brake cables. I can't tell it's there. The construction is all aluminum and seems sturdy enough. $8 shipped.
I was considering a dual cage set up, but it's pricey and doesn't look well made.
