How do I show a minimap in a 3D world?

Got a really typical use-case here. I have large map made up of hexagons and at any given time only a small section of the map is visible. To provide an overview of the complete map, I want to show a small 2D representation of the map in a corner of the screen.

What is the recommended approach for this in libgdx? Keep in mind the minimap must be updated when the currently visible section changes and when the map is updated.

I've found SpriteBatch(info here), but the warning label on it made me think twice:

A SpriteBatch is a pretty heavy object so you should only ever have one in your program.

I'm not sure I'm supposed to use the one SpriteBatch that I can have on the minimap, and I'm also not sure how to interpret "heavy" in this context.

Another thing to possibly keep in mind is that the minimap will probably be part of a larger UI, is there any way to integrate these two?