One more thing I just realized I could do is add the ability to upload an image file and then drag it around and rescale it until it fits the terrain.
For example, Army Map Service produced a lot of WW2 era maps:
https://maps.lib.utexas.edu/maps/ams/index.html
Italy Map Series
https://maps.lib.utexas.edu/maps/ams/italy_25k/
in particular:
(37.06644, 14.25024)
Gela Sheet 272-II SW, 1:25,000 (5.1 MB)
https://maps.lib.utexas.edu/maps/ams...-272-ii-sw.jpg
This way, you could combine modern DEM maps with WWII era maps to get a relatively accurate rendition of Gela, circa May 1943; via placing labels on the map; which you then use in the SPCAMO map editor as references.
