Southwest of the purple square on the map (the platform near mid-zone) is a ditch with a ShikNar Warrior or a Mature Rockhopper in it. If you go to the area with a tracker with sorting set to normal, it will always be on top of your track list as long as nothing else is repopping because someone killed nearby. This is because it despawns after less than a minute then respawns about ten seconds later. This is one (probably of many) ph for the fabled hoppper.
The PH spawns around -257, +787, waits a few seconds, then paths to about -110, +822 and despawns. This all takes under a minute. If you kill it nothing will respawn for the normal zone repop timer, so just leave it alone and watch the ph's cycle until fabled spawns. I can't run there from thought leech camp before it despawns so it's best to just wait at the hopper spawn and run for the fire idol if you need it also.
67 ranger in defiant w/ merc war did not find this guy to be a pushover, for reference. It was a reasonably close fight...
Have seen him pop back to back, and have waited an hour or two.