I usually enter Moonrise through the dock door which leads directly into the prison anyway don't go anywhere near the main entrance at this point, you can get to the dock door through the toll building and down some stairs (or cross over where you find Rolan later) and I haven't been to Last Light at all. Killing the guards outside on the docks works the same as killing the prison guards (i.e. no one notices).
kill the guards and the warden, toss Wulbren his hammer and then jump up onto the ledge (at the far end where all the barrels are) and go round the back - no need to open any doors.
Once round the back they are all standing there, so I flatten the wall myself with Thunderwave as noise doesn't matter given the guards are dead, then they all seem to come to life and run for the boat which is at the inside dock so no one to fight anyway. I travel with them on the boat. Seems to work out quite well. Only caveat is you have to get past the Last Light Jaheira interaction and then immediately run/fast travel to where Rolan is as otherwise the silly twit gets killed very quickly.
