Reading a bit more of BRP while I wrap up the character.
One thing I noticed that I thought might be a good fit for Midnight is the Powers system relative to the Midnight Heoric Paths. When I thought of running Midnight, one thing I considered was keeping Heroic Paths unknown to the players. Each time they level, I'd reveal a new power from their path. I thought this would add some excitement to leveling in a very low magic world. The Powers system in BRP might fit perfectly.
Not sure this really falls into a one nighter, but something to consider if the game evolves. If you haven't read the overview on Heroic Paths, take a quick peak. I think they describe it as that little detail that sort of separates a PC from your average Joe Blow in Midnight.