If you wanted more wagons,
it is possible to scratch build this type of supply wagon out of paper card, if like me one has a stash of old wheels, and horses. Well I never chuck anything away and over the years it fills up empty match boxes as if they were time capsules.
Replaced a broken HAT Wheel. Yes they most certainly do rot!
The canvas top cover can be made from screwed up paper soaked in a simple colour wash and overlaid and stuck on a form that fits snug onto and into the tiny oblong wagon box. Simple A 4 size paper will do,and with the process of screwing up and undoing it a few times it becomes quite soft with lots of good looking defined wrinkles.
With your ability to make your own buildings which stand in the background i foresee no great problem if at a later stage you made up one or a few. If one has no horses no problem either,just park them up. I made a few many years ago, and really they cost nothing at all. BB