Glacier, have you tried leaving some of your clothes in the area where he was spotted? We've had several instances in NH where owners lost there dogs in the woods. When they were spotted (or in the area where they were last seen), the owners left their coats/sweaters for the dog to find and smell and most importantly, stay. In all instances, the dogs stayed in that general area and the owners found them.

Perhaps you can leave a coat or a sweater or a shirt in that area?

Just a thought.

Good luck.