I was *thinking* about doing that with Gem, but have been just thinking of letting him relax forever. He's 8 turning 9 (he could be 9.. have to look at his papers) and he has mild arthritis (it's gotten a lot better). If he were to pull a cart, it would be small and light. But i'm sure pulling something can't be good for arthritis.
It was just a thought. Thanks for answering my questions!