I would also toss in some sand vs weights. It will keep the pack for getting cuts when hitting against hard objects. Curious if you’re packing up hill or flat. It would be more beneficial to use less weight and hike through a woods section with some dead fall. I have packed very few animals out flat roads.
I do think it’s realistic to pack 90lb+ pretty easily, just yesterday I packed salt and a cam up a shitty steep face only about 500 yards from the truck but 500 feet of elevation too, walking through loose rock, brush and dead fall. My pack had a 50lb salt block, screw gun, screws, camera, lockbox and lock, water, plus the weight of my pack and general items that are always in it. I’m guessing all together it was 75-80lbs.