If you don't mind voiding your warranty, you can have a shop put in another set of bottle bosses, two drilled holes, and two rivet type inserts, and you're golden. This is actually how your existing ones are done, so it is totally safe, just voids the warranty cause the manufacturers want to discourage stupid people from doing stupid things, and then wanting a new frame for doing it. On another note, have you tried the Wingnut packs? They are designed to carry VERY low, even the big packs put the weight down around your pelvis. You will forget that 100oz bladder is even there. Added bonus, going under blow down, no more snagging the pack and ripping it, or yourself off the bike. Check'em out @ wingnutgear.com. Other than that, there are a few systems that mount cages to your seat post, just get ready for a mouthful of organic matter using them in the dirt=
