For heavy loads I would see if I could get my hands on a Mc Kinley. If you cant find one of those, my next choice would be a Kelty. I have packed large loads in my Blacks Creek Alaskan, but for the big jobs, I want my external frame Mc Kinley. I have a camptrails moose pack which is one compartment that unzips in the front for getting the meat in and outand hasstraps to secure the load and keep it from landing low on your hips.

I have packed out 20+ bulls with this setup and have never had a back ache. For the shouler straps, I like to use fleece seatbelt covers from an auto store. It sure helps with the wear and tear of the straps.