I think I would just go and enclose the the upper porch area from the railings on up with hardware cloth, and go with a covered roof over that area. That way you would have a secure coop and enclosed run area for girls to get out and exercise during the day if you leave them locked up when you're away. Maybe get some cheap linolalim to put on the floor to protect the floor and make cleaning poops easier.
Plus, with your climate in Alabama, you're probably going to want something pretty open and airy for ventilation on those hot Alabama summer days. You'll have a lot of shade from the tree, but plenty of airflow for them will help as well.
I agree, making the whole upper part predator proof will be enough space for your 13 birds. You can lock them in the hard walled playhouse at night. Predator proofing the roof with a tree trunk in the middle will be a challenge, love to see what you come up with.
Thank you so much..... which door do you have? I have to look at these doors and figure out which one we should get...
I have the pullet-shut. It is a very well made and sturdy auto door that swings open on the side (you order right or left). Drill 4 holes in the wall and cut out the opening, bolts in place. Really easy. My coop is in a barn but if someone's door will be open to the elements (and they have snow), they might want to make an enclosed "porch" to keep the snow away from the door. It runs on a 12V battery and you can get a battery with either a plug in or solar charger. I've been running mine on 2 6V lantern batteries wired in series. It doesn't use much power. You can open or close the door any time you want with the provided magnet.
Programming the door open and close times is rudimentary - you open it at the time you want it open and the same day close it at the time you want it to close. Canceling 1 cancels the other. That is really the only drawback of the door, it would be great if they offered a programmable timer that could go in the port for the light sensor switch. I got the optional light sensor control so it opens relative to sunrise and sunset year round. I like that better than having to constantly reset the times as the seasons change. We get 15.5 hours of light this time of year but less than 9 mid December. I wouldn't want to have the girls stuck in the coop until 8:30 AM this time of year and wouldn't want the door open until 8:30 PM in December. You can put the sensor out in the open for the earliest and latest open/close (and it has to be pretty darned dark to close) or put it in a more light sheltered area to have it open later/ close sooner.