I made several of these cradle wagons. I mount my wagons on .40 inch thick sheet styrene from Evergreen Plastic. It is thick enough to be rigid but thin enough to cut easily. I also trim the corners so they are not sharp, it seems to draw they eye to it if they are not rounded.
A HaT soldier takes a short ride. My wargame rules require supplies and so making supply trucks and wagons is an important part of the wargame army. Units that are out of food or fuel, can't move. Units that are out of ammo can't shoot. Units that are out of medical supplies can't heal the sick and wounded.
Each supply vehicle gets a tonnage rating and that is how much it can carry of a given supply type. Horses can pull a wagon with 500 pounds, 1/4 ton per horse of supplies. These small one horse wagons between them bring a half ton on supplies to the front.