I found the slave camp before I found The Pitt guy. I killed the slavers, freed the slaves, talked to The Pitt guy and didn't choose the right dialog options. Then went back to Megaton to do a whole lot of other things before returning to The Pitt guy, and only by now did I found out that I did choose the wrong dialog options. So, I need a slave outfit.
Problem is, I went there around level 11, I'm 25 by now. I don't have a save game from then nor do I intend to start the game all over again.
How can I still aquire a slave outfit? Or is it impossible now to play this quest?