There looks like 8 stalls installed, but not active yet, at the east bound travel plaza in Rolling Prairie, IN.
3 S Knute Rockne Plaza, Rolling Prairie, IN 46371
This may be an odd source, but I was reading about a guys road trip experience in the mach e forum. In post 15 he describes the location and included a picture of the supercharger stalls taped off. https://www.macheforum.com/site/threads/1-100-mile-road-trip-impressions-on-mach-e-and-charging-infrastructure.5689/#post-162078