I use the Cabelas Alaskan frame pack. I'm not sure of the cubic space, but believe it to be around 5000. I use it for a week at a time and it has been great. The frame is also very sturdy as it supports a large load of that delicious elk meat. The bigger the pack the more unnessary items you will put in it as I'm sure you know. This pack is also very comfortable, as I have pack 3-4 miles with a 80lb load with no problems.