This guy took a bit of work to get to spawn, but not terrible.
He spawns in the Yakman caves on the Northwest corner of zone. Appears to spawn in dead-end rooms and not in hallways. I recommend entering the south most cave entrance, sticking to taking left hand turns only and killing all of the outward facing rooms all the way to the north most cave entrance. I wouldn't bother killing the interior facing rooms and/or the middle cave entrance. I did not see him spawn ever down there.
I saw him spawn in the east most room and the south most room, which aligns with others reports.
-2659.70 +3189.35 was my last spawn point.