Came here looking for an answer to the one-sided railing problem, but I just discovered the SOLUTION while experimenting. First create one staircase and place a railing on it. Then create a new staircase right next to it and place the same railing on the new set of stairs. When you delete the middle railing, it will also delete the most recent railing placed, but not the first railing. Voila, you now have a one-sided railing staircase! You can also delete the second set of stairs afterwards and the first set will remain as a one-sided railing staircase.