I need to move a flock of 10 hens and would like to use one of our wooden, "day-ranging" tractors that was built to fit perfectly between the wheel wells of our small truck. (We built these to move the girls around the yard but keep safe from predators.) It measures about 4' wide x 6' long x 3' high. It will be tarped, with a bungie net to hold it in place although movement would be extremely minimal as it was built to the dimensions of the opening in the truck bed. Perhaps a watermelon secured in the corner for hydration. Expect the trip to be 1-1.5 hours max of highway driving. My question is whether this is too much space for them to be safe or if I need to provide smaller spaces. Maybe some dog crates inside the tractor with 2 or 3 birds in each. Would rather not have to acquire the crates, but I want them to be safe.