OK, went back two saves and fought again. Found a new tactic other rangers may be interested in. Fire and immediately move a short distance left or right (heal if needed), repeat. No running needed. If you move fast enough, he misses. Just don't assume safety around a corner because he was still firing through the walls - but by not running, he doesn't start firing off screen. It didn't take very long to beat him this way and by staying close, the arrow spray gets more hits.
