We're constructing a tractor for our half-dozen bantams, and taking every measure we can to prevent predator attacks. I want to put wire on the bottom to prevent tunnelling, and minimize damage to the lawn. What size/type of wire is small enough to deter predators, but large enough that our bantys can scratch a bit in the grass? The sides will be 1/2" hardware cloth secured with screws and washers to keep out the coons. We do plan to lock the girls in the house part at night. Thanks!