We are building a tractor coop for our next flock of full size chickens (5-6 lbs full grown). Their coop is only occupied at night to sleep. They have portable pen that they go into at daybreak, or underneath the house in rainy weather. This tractor needs to be movable, since I move it every few days. I let them free range anytime I am home, which is most of the time. So, in order to keep it light enough for me to move it, what is the smallest square footage for 10-12 hens? Their nesting boxes separate...I am trying to decide whether I need to just make them two different coops and split them up. I would rather not, though.