[Maidhc O Casain]

The overlay image was a great suggestion! My process was as follows:

Used a snip tool to grab a pic of the map.
Opened it in Photoshop.
On a new layer, added in a scale bar from my CC3 files, and sized it to what I wanted.
Deleted the layer with the map, leaving the pic a very large blank layer with the scale bar properly positioned.

When I tried to import it, I got the warning Silveras mentioned regarding the images not being the same size, so I resized it to match in Photoshop.

It turned out great! The only issue is that every time I close the realm, when I come back to it I have to turn on the overlay again.

Is it OK to post a screenshot here? The pic of the map is IP, I know, so I don't want to violate that but I'd like to share the results...