Braxton Brigade
Songster
It would stay cooler than you'd think. It's a solid material (wooden) and they'd only go in it at nightfall and to lay an egg. I'm in Mississippi and we too get those awful triple digit summers and all the coops stay nice and cool, even the ones with metal roofs on them (go figure). The dog house would be no different than any other coop in your area just smaller than the typical coop, the dog house is practically the same as a coop you were looking at in many ways. In the summer I make sure my girls have shade, cool water and I choose to set up a box fan that blows into their run.