Go ahead, buy three different packs for different sections of your ascentgood luck carrying them all. If you'd rather not strap packs onto your packs, you can just bring the lightweight Mountain Hardwear South Col 70 Outdry Backpack, which is basically three packs in one. It's got plenty of space for a two day winter mountaineering trip, and strips down to the basics to help on the summit push you can pop off the top pocket, slide out the padded Hardwave suspension framesheet and aluminum stay, reduce the padded waist belt to a simple nylon webbing belt, and go fast 'n' light all the way to the top. When you're carrying a heavier load, leave the suspension in and walk cross country in comfort. Along with rugged nylon fabrics, the South Col is kitted out with an OutDry waterproof membrane, which will keep all the gear in the main pocket dry as a bone, and features a front zip pocket that's easily accessible and maintains its volume, even if the bag is stuffed full. There are tons of lash points and straps for carrying skis, ice axes, and poles, an easy access crampon stash pocket, and a top skirt that extends to give you an extra 300 cubic inches of space. Never bring two packs again.