When you take the wheels off it sits flat. But I do want to move it around daily but at night what would be the best way to make it so no animals can dig their way in?
One thing you can do is add a 1' wide machine fabric "apron" around the outside. Use a bungie cord or clip to hold it up off the ground when moving the tractor, but let it lay flat on the ground during the day. Digging animals will start digging at the edge of the vertical fencing and be standing on the wire apron and not be able to dig in.