You guys might want to check this goodie out if you're going light, I just crammed a week's worth of grub into mine WITH ROOM FOR MORE! it has a canteen pouch [or tablet if you're wired.] and a cell phone pouch that holds a gerber tool nicely. https://www.overstock.com/Luggage-Bags/Everest-19-inch-Deluxe-Sling-Backpack/7706267/product.html
I have a Sling Back Pack, not the same Brand as the one described in the Link, and not quite as big. I don't think mine is big enough to hold a Weeks worth of Grub, but Three Days is probably doable. It has a large inner Pocket, and Two smaller Pockets on the front, with lots of places to attach other Pouches or Gear. I think the Brand is Red Mountain.
