I think you'd be better off around the Forest Hill end of Dartmouth or Honor Oak Roads, or Taymount Rise. That way you have the N176 handy, and the P4, 176 and 185 during the day. You would be near the Hob and Dartmouth Arms.

Another option could be the N end of Honor Oak, where you could catch a very swift (although rather infrequent) train to Denmark Hill from Crofton Park. Honor Oak Park station would still be better for town, and as mentioned there is the N171 night bus, which would get you back from Camberwell Green if you fancied braving it after any funny shifts you might have, or indeed after a night out at The Venue in New Cross (whioch doesn't constitute a recommendation!)