You may want to look into taking fresh and frozen foods with you.  Kondos has an insulated food pack that supposedly works pretty well.  Of course this increases weight, and during the hotter months will only keep food cold for 4-5 days, so isn't completely reliable for a long trek.

There are plenty of organic, relatively shelf-stable options out there at Whole Foods and other similar retailers.  Plus, you can always make your own energy bars, granola, etc.