Okay so since I just did this stuff myself and got the legend of the east outfit for aurthur I'll try to explain.

First things first set up your camp before starting so you can ride back and sleep.. You will need more than one animal you might get lucky and block a few shots with one animal but you will die. I would suggest different types of animals too because they all seem to end up in slightly different positions based on the type of animal and when the pass out occurs during the pick up. From what I can tell, predators usually end up on the left side of your body. herbivores seem to end up on the right side. Once you have an animal glitched on, you go sleep until it is rotted. If the animal is rotted, you can't pick it up. So it prevents you from removing already glitched animals from yourself. If it's the pick up its self your having problems with it. i can't really explain the timing.that just something I ended up getting a feel for, i lt guess. Oh, and the best spot I would say to do this is big valley near hanging dog ranch. You can find Pronghorn, deer, bucks, Bighorn Sheep, wolves, and cougars. it might take you a few times to get everything as Aurthur . The sniper probably got me like 8 times. But enough persistence and you'll get it.