Is there any way to show a thumbnail for the map?

…Or otherwise to show the same map (and the same pieces on it) at different zoom levels simultaneously?

The component you’re looking for is the Overview Map.

Yes, I suppose that is basically what I was going for, but is there any way to move it around or otherwise reconfigure it while that window is active? Or is it just purely an on/off toggle? Is there any way to make it not cover the normal map window?

The overview map is good as like a minimap (which will crudely accomplish my objective if there’s no better option), but I’m looking for something that’s more like a persistent split-screen type of deal with both windows taking up about half of the screen, and one just shows a more zoomed-in chunk of the map (as opposed to either something really small, or something you turn on and off). I guess thumbnail wasn’t really the right word.

Like, if you were playing Avalon Hill’s D-Day, picture it where you can see the entire board on one half of the screen, and just the Brittany landing zone on the other (but with the option to zoom out a little wider). That’s basically what I’m going for.

Sorry, no. The Overview Map is not very configurable. You can adjust the scale, but not much else.