This guide is for doing it on the hardest difficulty [Tier 4] with a thief, which is actually pretty easy once you know what to do.
Zerk gear will definately work; I used a mix of soldier/valkyrie/and berserker gear and still had more than enough DPS to burst the plunderers down. S/P and scorpion wire will make this a piece of cake. You pretty much just need to stand at the back and reel the plunders in with scorpion wire then use pistol whip once to kill them. Infiltrator strike if by chance one is still not dead.
Note: Let the third plunder escape so none of them spawn on the right side.