Most folks don't realize that for each thing you see on display in a museum, there's probably a hundred more stored in their archives. That stuff in the back room might not be quite as pretty as the stuff out front, or it might simply not fit in with their current display. But ask the right person and you can learn lots about what is back there, and in some cases you might even get invited back to look at it.
I'd sure find a museum that has stuff from the era you're interested in, then politely and sincerely start to ask questions. There's tons of stuff in the back of most museums that's never been on public display, much less written up in books. And to go with it, there's usually a researcher that knows a whole lot about it and will be proud that you're interested.