i have found kingshead to be better usually (for me), (quiet server) since fort charles is usually pretty busy,
as a level 12 noob, i would enter the fort, and the doors' either guarded by a vet or a sarge, or 2 of each etc. and id simply run behind the fence, attune, and safely rep my doll up.
dagger skills help, using the knife throw to get their attention after they spawn, run up and attune, while they harmlessly stay on their side of the fence
and with the bonus of 2 enemies to attune, it was usually peaceful and not very hectic.
(im talking about the first fence here, not the fence everyone uses to train nades against the squad)