How big of a chicken tractor would you recommend for 6 chickens? We already have a perm. coop and run for 12 chickens total. But, I just got 6 more pullets (for a total of 12). And they are about 6 weeks old. Until they are big enough to put in with the other 6 chix, I want to put them in a tractor during the day and then after the move to the perm. coop, I want to continue to use the tractor for half the flock at a time. What do you guys think?