While doing some research, I stumbled across this record attempt by the AM-Trackers of Switzerland. Using four locomotives and 134 bathtub gondolas, they ran a train that was 44 meters long. That's a little over 144 feet. The layout itself was about 400 meters long with very broad curves. Pretty impressive. I think I recognize a couple of the members from a group that visited AGHR several years ago. Check out the video. Hope you understand German.