Look at Kifaru packs. I bought one before hunting Alaska last year and really like it. With a removable top that can be made into a day pack, the pack has huge capacity, but can be cinched down to be really compact. It is relatively light compared to other packs that have 6000-7000 in. Capacity.
I would have also recommended the Kifaru Timberline 2, Bikine/Timberline 2, or Bikini/Highcamp, but the wait time on one right now will put him well into hunting season. I think Schnees might have the Stone Glacier in stock, and it is a fine pack as well, and a bit lighter.