When I drag my bear out I cut two poles about 10 ft long.Then lash some smaller cross pieces to it like a stretcher. Then tie bear or deer on and drag out.I have moved them over 4 miles this way.The last bear I shot spring of 2014 I did it a little different. I cut 2 poles and tied them to my pack frame then strapped on the bear. It worked also. Thinking about packing a small wheel and lag screw or some sort of brackets for an axle to make it easier. Game carts would be a chore to pack in where I hunt. I like to keep it light.
Good luck.