Also, bear in mind that prefab coop companies use the same space standards as egg farms, 1 sq foot per bird. You know those videos of factory farms that show rows and rows of hens squished in cages? Those are those measurements.
2, max. I've also seen them. They included the next boxes in their measurements. They fall apart well in two years and I've personally seen the aftermath of coons pushing their esy in through the next box floor.