Hello I would Like to build cheap chicken run. But I have near.by dogs and my fencing is low all the way around.. And my neighbor has had chickens killed by a possum. 1st. PVC Chickens Run cheap and easy build? 2nd is it predator proof? Even if I make it mobile? 3rd. Is possible make both run and coop (coop made out pallets) mobile? Also plans or links to how to instructions greatly appreciated..