We don't have the foggiest idea what color Kennewick Man's skin was.
If we can use his present day Ainu ancestors as a guide, he would be tall, hairy and light skinned. Kennewick Man is 9,300 years old. The oldest (undisputed) Mongoloid skeleton ever found is only 10,000 years old. It is my theory that the Jomon/Ainu dominated large areas of Asia in ancient times and the Caucasians and Mongoloids both are a 'branch' from that line.
http://www.pbs.org/wgbh/nova/first/kennewick.html
Go argue w these guys.