Not to diminish your inventiveness, there was a G scale train at Trainfest 5 or 6 years back with a weiner mobile "engine" and slinky cars in tow. They put a clear cylinder around the spring to keep it from slinkying. It might have looked better inside the spring or put a clear rod in the middle. It is a good idea as evidenced by the fact that I remembered it (I don't remember today's lunch).
Brendan
