And the first contra-terrene battleship was... Oh, still waiting.

Sorry, just teasing.
Not sure if this helps, but might I still suggest you peruse some other forums here?
Historical: Pikes, Muskets and Flouncy Shirts, Age of Big Battalions, and Colonial Adventures. I do troll the last for VSF situations and directions, but all may fire your imagination for items that may qualify as crossovers.
Broken Record Talk: Gothic Horror. While Dracula and Frankenstein were more modern stories than most realize, as Bram Stoker was criticized for such as Mina keeping notes on a typewriter, the folks having fun on the forum seem unbounded by time-and-place.

Not much help, I assume, but please do keep us apprised of your progress.
Doug