Now THAT would be handy. I know some people who use their horses to pack their deer out. I don't know how they ever train the horse to do it. Seems like the smell of all the blood would really freak them out.
Have you ever considered training him to a cart? That seems like it would be fun. One of my riding buddies has trained all of his horses to a wagon. You know, the home built kind with car tires. That way he can load up his wife and grandkids and take them for a ride too. He even fixed his wagon to work 3-abreast. Another guy I used to ride with would take his horse out on trails, and some pretty rough ones, in a little 2-wheel home-built job made of tubular steel and motorcycle tires. It was interesting riding along behind him. The old Racking Horse gelding that he used could FLY! The guy was insane, or had a deathwish, I'm not sure which. ;o)