If he is crate trained, I'd crate him while you are gone. My 13 yr old girl who has been crate trained her entire life, suddenly started stressing last year.
We still crate our boy, but we put her in the kitchen area - pull the bathroom door open and latch it to keep her out of the bedroom, and then put a baby gate across at the other end of the kitchen. She does better that way.
I close the curtains, set the a/c, set up battery operated fans in case of power outage, and let the tv on low.
I keep the dogs confined so they can't get up and look out the windows to see the outside activity.