I've done a fair bit of backpacking and a fair bit of hunting, but I haven't combined the two a lot.
When I'm hunting "normally" I cover a lot of ground in a day. For instance, I got my deer last year toward the end of a day where I'd hiked 16 miles, mixed abandoned roads, old trails, and cross country. For that a Badlands 2200 or similar works good, a little big for a day pack, but you' don't have to go back.
When I backpack in and camp to hunt, I usually set up camp within a mile or so of where I plan to hunt. Under those conditions I usually don't carry a pack, instead, something more along the lines of a "possibles bag" with just bare essentials.
