Welcome to BYC.

from the NC Sandhills.
As a fellow resident of the Steamy Southeast, here's an article for you:
https://www.backyardchickens.com/articles/hot-climate-chicken-housing-and-care.77263/
The Usual Guidelines
For each adult, standard-sized hen you need:
- 4 square feet in the coop (.37 square meters)
- 10 square feet in the run (.93 square meters),
- 1 linear foot of roost (.3 meters),
- 1/4 of a nest box,
- And 1 square foot (.09 square meters) of permanent, 24/7/365 ventilation, preferably located over the birds' heads when they're sitting on the roost.
BUT, here in the Steamy Southeast, I find that it usually takes either DEEP shade or a minimum of double to triple the suggested minimum ventilation to keep the coop under 100F on a 90F day.
One of the problems with A-frame designs is that they're dreadfully-hard to ventilate -- if you make them rain-proof by extending the roof down to the ground then there's no airflow. And if you're going to put them in the sun you don't have a coop, you have a rotisserie.
The best coop design for a hot climate is an Open Air style -- essentially a roofed wire box with a 3-sided shelter at one end. This one, a hoop tractor version, is a good design:
https://www.backyardchickens.com/articles/hoop-tractor.69336/ I myself would make it possible to roll up the tarps on the sides and leave a vent at the top of the back as well because airFLOW is key.
The plans you're looking at are too small for your proposed flock.
6 hens
- 24 square feet in the coop. 4'x6' is the only really practical build for this given the common dimensions of lumber. If you can't walk into it, put the access door in the middle of the long side to make sure you can reach all areas of the coop because a stubborn chicken WILL press itself into/lay an egg in the back corner where you can't reach.
- 6 feet of roost
- 60 square feet in the run. 6'x10' or 8'x8'.
- 6 square feet of ventilation.
- 2 nest boxes, to give the hens a choice
You see that, at 6x10, it's only big enough to be the run for 6 birds, not the coop and run together.
It's also wasting space by having too many nests -- one of my rules of thumb is that a coop design with too many nests shows that the designer didn't know much about chickens' actual needs and thus it probably has other flaws too.
Why do you want a tractor specifically? Do you have photos of the yard where you plan to keep them?