Your total pack weight for a week's trip could be close to 15 lbs. more than your base weight, which means you need a pack that will support 30 lbs. This definitely means no frameless packs, if you want to be comfortable. The ones with added stays should be fine, if they fit properly. I'd suggest getting a pack that the manufacturer says will carry 5 lbs. more than your maximum possible total pack weight, just to be on the safe side.
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May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey