GossamerGear G4 or GoLite Gust. both very good choices.
G4 has better organization capabilities (if that is impt. to you). perhaps a bit more "fragile" than the Gust if you need to "bushwack". i own the smaller, more fragile G5 - very nice pack, but too small for your requirements perhaps. GossamerGear is a top-notch company; very trustworthy; ship immediately. you can order a "Semi-Custom" G4 in heavier, stronger, more robust Oxford cloth, but the price is a bit more. 5 days food is no problem in the G5, but the rest of your gear needs to be very light weight & highly compressible (for those items that compress). G5 is a more expensive pack, extremely light weight, & a less robust fabric - not recommended if bushwacking is a must.
Gust - i own an '03 Gust - Spectra fabric. newer Dyneema not much different. very robust material. nice pack, but a little anemic in the external pocket category. have seen plans on the web for making/attaching easy to reach side pockets - but i forget the link. this appeared easy to do. do a web search, i'm sure that you will find the link.
G4 is around 16oz. (depending upon options and material, if semi-custom), & the Gust is a bit heavier (19-20ozs depending upon model year).
both req. the use of a "virtual frame" constructed of your sleeping pad. the main diff is that in the Gust, you roll your sleeping pad into a cylinder & put it in the pack first. the G4 has an external pad pocket. you fold the pad (30"-40"max pad length) & place it in the pad pocket which then "rides" against your back for cushioning. this leaves more space inside the pack's main compartment for your gear/food. structurally, a cylinder is stronger than the folded pad, but i haven't had any problems with "frame collapse" using either pack with 19-20lb total pack weight.
hope this info helps.