Take a look at ULA packs as a possible option. Maybe the Ohm?

Whether or not you could use a frameless pack partly depends on how much you'll be adding to those 7 lbs! 2 weeks' food will put you in the definitely framed category.

I know I can't use a completely frameless pack of more than 10 lbs, but that's me. Having a good stiff foam pad helps a little. On the other hand, my backpack will carry up to 35 lbs (not that my knees and feet will stand for it), and it has simply two aluminum stays, to which I add a foam sit pad. I can't reommend it, though because I bought it as a discontinued model in early 2006.