Jack, yes that's a splendid effort. It always seems a shame that there is such little interest in trailers of any era. I have a certain fascination for military tentage & it really brings to life wartime footage being able to recognise the various tentage used. As logistics & supply have more interest to me than the fighting bit. Anyway enough of my other weaknesses, I see the driver on your cart was perched up on the top, how usual was that I don't know & whether there would be as much control sat up there as on one of the horses. See below:
Cart, Water Tank, Mark VI