Here is a little trick I came up with many moons ago when most of the meat bags out there were just the cheese cloth jobbers and not strong enough to hold crapola. I safe up some of those red colored nylon onion bags. If the weather is warm you can hang the boned out meat and air and cool the meat and pull one of the cheese cloth bags over it. Put backstraps/tenderloins in one, cut roasts and throw it in another, etc... you get the idea.
Also works well to slide inide of small trash bags. If you are using your actual backpack bag you this will keep it from becoming a bloody mess as well as allowing you to layer your load inside your pack to keep everything from being balled up in the bottom.
I ordered some material that is a bit stronger and working on sewing up some bags that would buckle into my NICE frame in combo with my Longbow bag. Best of luck, I hope you get to enjoy that sweet misery of an overloaded pack. I have been lucky enough to kill better than 30 elk, only had three come out in one piece. Happy hunting, Casey