The Pintler's 2,500 cubic inches, I've managed a tent, pad, bag, bivy, stove, food, water, layers of clothes in that volume (2,400 Kifaru Molle Express) for winter snowshoeing overnights. As others have mentioned, you could put your sleep system/shelter underneath leaving more room inside, without even using the meat shelf. Watch the good idea fairy video, and start chucking stuff you can live without. Lower pack weight means faster you....