There was a game that did pack mules and it was just that, a mule with a bunch of bags on it. It's called Dungeon Siege 2. I don't remember if the first Dungeon Siege did it but this one did, and it was a great game element. It was a great way of solving the whole "11 battle axes in a pouch" problem. One of my fondest memories of the pack mule is actually of it dying. I'm an item hoarder in all games, and I had that thing bulging with goods. Funny thing is, that when your pack mule dies, all of it's contents are thrown out on the ground. It was a grand explosion. So upon returning to my body and my mules body, the entire dungeon floor was riddled with gold and items. Good times...