Well, here's how the watercolor situation resolved itself.

I went and had the map scanned in high res at a local office supplies store with a large enough scanner.

I failed to look at the scans closely enough before I then took the maps to get framed.

When I began to inspect the scan, I realized its settings were calibrated for too high of a contrast, and the color washes were not picked up at all: the scan only showed white areas.

So I've had to go back and digitally touch up the scan so it reflects the gradiated watercolor washes in a manner close to the physical original.

All in all, it will do.

EasternLC-Map-Composite-Watercolors.png