Some ideas of mine:
* Move the whole setup closer to the afternoon shade.
* Add a shade tarp over the coop.
* Paint the roof white.
* Increase ventilation (I see you're already planning to do that).
* Add a small fan (solar powered?) to help pull cooler air in and force hotter air out.
* Add a roof vent.
* Freeze water in soda bottles or milk jugs, and throw those inside during the heat of the day. They last a surprisingly long time, and my birds huddle next to them when they're too hot. On 100-degree days, they'll last pretty well from 12noon to 5pm.
* Move the whole setup closer to the afternoon shade.
* Add a shade tarp over the coop.
* Paint the roof white.
* Increase ventilation (I see you're already planning to do that).
* Add a small fan (solar powered?) to help pull cooler air in and force hotter air out.
* Add a roof vent.
* Freeze water in soda bottles or milk jugs, and throw those inside during the heat of the day. They last a surprisingly long time, and my birds huddle next to them when they're too hot. On 100-degree days, they'll last pretty well from 12noon to 5pm.