Again, thank you for the kind comments!
Pencil lines - As I said above the lines are only meant to help me during gluing/assembling so I glue them correctly so that the "detailed" side is visible.
Three at a time - I don't know really... For some reason when I thought about how to do the gallows I wanted to have it larger from the start. Now that I wrote a scenario for it I realize how good a decision this was. One player has to free the three captives, each freed one (who escapes off the board) provides 1 victory point. This way you can clearly determine a scenario winner while experiencing a mix of saved and lost captives. Additionally, during a campaign you can play this scenario once three members of your Crew/warband/group have been captured by the authorities. I think it is a good decision from a game design perspective.
So I can definately recommend doing such a piece. It's fun little project with a lot of gaming potential.