Jeremy,
I have the Halftrack but I feel for what you are looking for the Eberlestock J34. It will be a better hunting pack. Is what is great about this pack is it has a built in scabbard that I use for my tripod when I am not carrying a gun, which is most of the time. I use this pack and it is great.
Once you use a scabbard you will never go back to a pack without one. The J34 is also a packing machine with the built in metal frame. It will take care of all your needs you talked about.
The Blue Widow is a great pack, just a little larger than the J34 but it doesn't have a scabbard. With the J34 you will have lots of room when completely expanded. You can also add a "Super Spike duffel" on to the pack with zippers on if you need more room.
One sad note, Eberlestock's warehouse burnt down 2 weeks ago and lost half their stock, including all the J34's. So finding one at this time is going to be tough.
Contact me if you need more information or if you would like to talk about all options. Hope this helps.
Eric