I have a Selle SMP Lite 209 saddle that sits very far forward. I tried a PRO Aerofuel Tri Cage but as seen in the attached pictures, the rails that it fits are too far forward and blocked by the seatpost and the exposed rails flare out (and up) too much.
I use the SMP Pro saddle, and modified an older XLab carrier to fit. Photo: http://i58.tinypic.com/213qiiq.jpg . Basically the attachment points to the saddle rails were cut off (say 1-2") with new bends in the aluminum (with mounting holes for the eye straps) to match the saddle profile. I did this to get the carrier closer to the end of the saddle (not hanging out too far) and with a more upright bottle placement. I don’t know if this model is still manufactured but you could modify a Turbo mount. Use it with Specialized RIB cages as I think these are the best holding cages.
A single carrier is the Specialized one, but, again, modified for the saddle rails. Photo: http://tinypic.com/view.php?pic=m7qq1e&s=8 . This is the Specialized Reserve Pack single-mount system, but the top rail mount (into which the bottom carrier arm and bolt attach) must have some filing or grinding done to match the rail profile to seat properly. I mounted the carrier where I wanted it to sit on the rails (bottom of rails at turn between vertical and horizontal), inked the mounting point for the saddle rails, removed the holder and with a bench grinder and file ground the top mount a bit to get it to seat properly into the saddle rails. In effect, you create a small channel to hold the mount in place a bit more securely. I also use a RIB cage and it securely holds a bottle in the cage w/o drops.
I had to bend the brackets on the RML to work, but it wasn’t difficult and made for a really solid mount. It’s a tight fit along the top of the mount/bottom of the saddle, but I think you should be able to get it in there, even with the saddle forward. If I think of it, I could send a picture - one of the bikes belongs to a guy who trains with me in my basement, so the bike is handy.
i’ll second this option, and you can turn it pointing up too to get the bottle closer to your butt(out of the air)
i have an SMP Evo Strike on myQR Caliente.
Minoura SBH-80 Single Water Bottle Cage Mount for Behind Seat