What are the names of the perennials that you used in the mock up?

Coneflowers, Blackeyed Susans, Catmint, Leadwort, Switch Grass & Pugster Butterfly bush

You might want to find out at your local nurseries what they have for your zone.

In zone 7a I'd want evergreens primarily.

Good idea to go with evergreens.

And before anything else, I'd plan for shade from the hottest sun of the day--the west. Shade cloth/pergolas/etc don't compare with leafy shade from trees. It doesn't have to be a tall tree--smaller trees properly planted will provide shade in a few years.