I have a 5600cu frame pack (Kelty Super Tioga) - its a week pack, and very comfortable. It'd be great if I had to hike out of somewhere, but probably not as good if it was a "$hit hit the fan" situation, because I can't really run with it. If I need to break that down in to a smaller package, I'd just throw it in my old Large military Ruck w/ frame - I'd guess its about 3500 cu or so (I just looked - they're cheap online - make sure to get the frame and kidney pad though!).