I think it's the new Tamiya 1/35th scale Mk I kit. It comes motorised as standard and you can build several marks from the kit.
Obviously you need to keep the heat away from the plastic. I couldn't see how else you could do that except to have the boiler away from the body of the kit. I've never seen or heard of Mark 1's pulling trailers but I'm willing to bet it was tried at some point. Very nice work!
