green horn,
sorry if this has been asked, but how much riding have you done? More to the point, have you ever ridden a fully loaded touring bike? What kinds of adjustments have you made to try and cope with issues you may have had?
I think the problem people are having with your idea is that it's a fix to a problem that doesn't exist in their eyes. If you have some real evidence, maybe a blog from a tour or something to that effect with pictures and stories of how you would prefer your bike to be configured a certain way and why, then your ideas would have more merit to this community.
Actually seeing your current bike may help quite a bit if you have a picture. Perhaps you don't need a redesign so much as a readjustment and some nice equipment.
The reason I ask is really the 20 gallon argument you made. I have read of people crossing remote sections of the himalayas without near that much water.