As a long time backpacker and backcountry hunter I can say with authority that, nice as they are for military use, Eberlestock packs for hunting are TOO HEAVY by several pounds.
I recommend an internal frame pack that is made to carry 80 lbs. Deuter has some good ones like the Air Contact Lite 65 + 10 (75 liter max capacity). Others are Osprey's big packs, Kelty, Gregory, The North Face and REI.
A good external frame pack would be Seek Outside. Many hunters love them.
Remember, you are carrying a rifle, ammo, butchering gear and game bags IN ADDITION to your backpacking gear.
And elk hunting usually requires hoofing it at around 7,000 to 10,00 feet, where air is thin and hunters tire easily. Weight you carry becomes extremely important at that point.
i recommend hiking poles and buy a pair of Quick siX to quickly mate them and have solid shooting bipod sticks.