I have killed about 100+ of these. The camp that is NW of Bjarken is a great spot and you can pull from three camps to keep the camp bonus up to speed up your leveling.
If you head North from Bjarken and follow the path you will find the area with the Berkland Providers. From here turn West and go up the hill. You will see a path in the mountain. Follow this until it branches and take the right fork. There will be two Streebers guarding the entrance. These might be on a 4th camp bonus as well. The area behind them goes left and right. Each end will have a seperate camp bonus and the ones in the middle have one as well.
I generally pulled from the wall (RM, RC spec) and could nuke most before they got into melee range.
I have about 8 Focus staves and each has a different bonus to it so it was nice being able to pick which one to use and which to hand off to alts or salvage. In addition you can get ROG items and the two kill task items mentioned. I have 7 Heads and 4 Scalps and they stack so it does not take up much room. XP for each is in the 1.6M range and both get turned into NPCs in Bjarken.