I use that exact same frame pack. Last week I helped pack out an elk. I had a hind quarter, a front quarter and my Eberlestock slingshot pack all on it at the same time.
I was truely glad my buddy shot the elk up the hill and not down the hill!!! I dont recommend carrying that much weight, but at least I know it can do it, and I sorta can! If you count falling over like a lead shelled turtle half a dozen times or more on the way down.
In all seriousness, it was tremedously well supportive of a very heavy load.
I hunt because........