I haven't looked into classes lately, but McMillan used to offer a long range rifle class. Front Site in Prescott also offers a long range class, but only after you have completed their basic rifle class first. Both options were very pricey when I last looked into them.
Shawn Carlock of Idaho runs a great long range class. He is a sponsor here, and Len Backus had him open another class for this summer. Last I saw, there were still two slots open. Google "Defensive Edge" and you will find him.
Another option is "Rifles Only" out of Texas. They run a great class as well.
Maybe if there was enough interest from us shooters down in AZ, we could entice someone like Shawn to escape the cold and snow in Idaho in January and come down to balmy Phoenix for a clinic!