you might want to consult a vet for his extra sweating. I have a dark horse, who gets extra warm during hot days, but he rarely sweats on his own (unless he loses his mind and runs around like a nutcase), but he dries quite quickly after work.
I know a mare that will run herself soaking wet when big bloodsuckers are around. She really hates them.
About clipping, I meant that this late in summer a horse should not be clipped, because that will mainly ruin his looks for summer. There has to be a reason why he is like that. Maybe there is too much work for him, or he is stressing about something? Does the sweat collect in working areas (shoulder, chest, neck, behind hind legs, a bit on flanks), or does he get soaked all over?
I play games with Hulk and a fire breathing dragon.. Love it.