Hello Ralph,
At our Club (Balne Moor) tug towing developed just as Umi describes.
We still have scale steering competitions, but have a lot of tug towing events which provide a greater/different challenge. Below are a couple of photos which show each of the two towed vessels we own. The link at the foot of this post will take you to our we site where you'll find a lot more photos from the 2018 season. On the Events at the Pond page you can find the rules we use for towing - scroll to the foot of that page.
I like the idea of extra challenge as Umi has shown in the dockside photos from her Club