We don't usually play with the expansion maps so I sometimes forget to take them into account. I may change the target location for the kidnappers from the River Docks to any aquatic location in order to take into account the expansion maps. That will change a few other things as well but overall I think it should keep with the theme.
I agree with the problem of space on the board. Any easy fix would be to just discard an ally at random when the kidnapper is successful. I however like the idea of letting the players see a specific ally get kidnapped and then discarded if they choose to do nothing about it. For the same reason I want to keep Ma's Boarding House open. I like the idea of giving players the option to take allies from the deck as normal but now with the risk of the scenario being fulfilled.
I also like the idea of using the jail but I think this scenario gets to rules heavy with it. I have a few other scenarios I am working on and I might use it in one of those.
Thank you for the feedback. =)