Hi, we just got our first chicks and will be building a chicken tractor that needs to keep them comfortable through a cold northern Minnesota winter. We will have about 12 chickens, and would like a design that is light enough for two people to move around in the summer. I can insulate the interior if necessary, and could provide a heat lamp on those *really* cold nights (we get to -40F at times). I have alot of building experience and plenty of tools, so I should be able to build just about anything...we appreciate any suggestions you can give us!