Hello and welcome to BYC, You found an Awesome poultry Forum to be a part of with many great knowledgeable members who are more then willing to jump in and help you with any questions you may have.
Hi & welcome to BYC! I'm in Texas. Hot weather chickens that I love and have had good luck with are necked necks, welsummers, langshan, and cream legbars. I don't have any leghorns but they do well in the heat too.
As far as keeping them safe, use a lot of hardware cloth and stay away from chicken wire.
Good luck and enjoy!
Hello and welcome to BYC! Glad you joined.
Research Mediterranean breeds.
Build a large open air coop using 1/2" hardware cloth.
Build the coop and run on high ground that drain away from the structure all the way around to keep it dry.
Install a 2' wide predator apron around your entire setup and have no gap larger than 1/2" to keep out most predators.
Put a solid roof on the run and try to put the entire setup in deep shade.
Put out a kiddie pool with a big chunk of ice in it to slowly melt and give the girls cool water to drink and wade in.
Run floor fans across the run to help cool them off.
Give them a mash with electrolytes in it during extreme heat to help them cope better.