Careful using that clear polycarb roofing! I tried it last winter for a coop I was only needing to use in the wintertime; this June, it registered a toasty 117 degrees inside that coop one sunny afternoon, more than 20 degrees hotter than the ambient outdoor temperature. When your daytime highs run into the 90's, you really don't need your coop getting any warmer.
I would worry less about square footage inside the coop than I would worry about scrimping on square footage in the run. Your birds are likely to use the coop only for roosting, so floor space isn't going to be as important as roost space. As long as you can manage to fit in enough roost space, your birds should do fine with a bit less than the 4 square feet per bird floor space.
I would worry less about square footage inside the coop than I would worry about scrimping on square footage in the run. Your birds are likely to use the coop only for roosting, so floor space isn't going to be as important as roost space. As long as you can manage to fit in enough roost space, your birds should do fine with a bit less than the 4 square feet per bird floor space.