Glenn, I've gradually dropped the weight of my gear so that even on very long hikes I'm rarely over about 17 or 18 pounds, and it all fits well in less than forty litres (though I rarely carry more than five or six days of food at a time).

I use a custom MLD burn that (on my back) carries exceptionally well. I actually had 26 pounds in it for a little over a day once and it still carried very well. The pack (with belt pockets) weighs just less than a pound (I took off some bungee cord and hardware I never used). It has no frame, but I wrap my neoair around the inside and it works fine, even at maximum load.

Best, jcp