Any of the newer pack designs that separate the bag from the frame for load hauling are perfect, don't go any smaller than 5500 bag, 6000-7500 is better for sure
I use a MR Nice Frame/5500 bag and I have no problem putting 70 lbs worth of gear in it and thats about as much as I would want to carry for any extended periods of time.
At least if you have a bigger bag and the option of putting meat/horns between your back and the bag your all set.

I robbed this picture off the EXO Mountain Gear website for an example