Ok so I just got to day 20 (needed to replay it) the bandits attacked bareshed, Logan tells you about the location of the camp. NOW to unlock the fight with scar and tank you eavesdrop on them in the track at night.
Ok so (just got done playing through it another time) you have to at least have met jester till you were able to speak with him freely. Go to the track at night and you'll eavesdrop, (I guess it is random) go back to jester and exhaust all of the dialogue options then the next day you'll ba able to begin infiltration (which is basically the battle with tank and scar)