My only comment is that while my EEs do great in Texas heat, and they have never gone over the 4 foot fence, I have one that if lock in the run, can get over a six foot fence. Chickie jail, also known as the run, seems to insult one of my EEs and she always gets out. She has never left the yard, though, and I know she can get over that fence. I love my RIRs personalities and the BOs are great too.
I started on with four in my suburban back yard, and now, one year later, I have 10. Make sure you have room for more then the 3 you plan for.