He is a triggered spawn. You have to walk on JUST the right spot, apparently, to spawn him.
In Antonica, near The Settler Camp directly south of the Qeynos Tower griffon station near 350.35, -22.59, 618.19 . He should have a tent on top of the hill.
In The Commonlands: Go to the northwest gate of The Crossroads, walk southwest along the moat to a rock at -382,-45,-295 , and then walk due west towards the water. Turn and he should pop right behind you.
In Darklight Wood, at the southern end of Innoruuk's scar near 536, -54, 51 .