Some more info posted by the official FB page
(top post + response in comments)
-- His shoe, and sweater with glass in it, were found down hill from the accident
-- Police have said they believe the driver window was knocked out from the inside
Sounds like he bashed his head bad and walked away confused.
But his missing ID and cash, the unsuccessful searches with dogs and drones and on foot, and no one knowing what he was doing hours away from home... ??
eta: Site of crash on left side. He was driving north, but judging by the pictures seems like the truck was on the wrong side for some time.
خرائط Google