I want to remove most of the detail from this image:

Specifically I want:
1. Solid blue for the sea, with a distinct coast line (that doesn't need precision).
2. Solid green for the land.
3. But keep the white place names and their tiny circular markers.
Am I on a fool's errand, or can this be accomplished please?
Here's the original BMP:
https://www.dropbox.com/s/8e7y3n4coeici ... 1.bmp?dl=0
I'm still working mostly in PSP 8 but happy to try it in PSP 2018 if that has significant advantages. And, of course, if it requires many steps as I expect then a script would be ideal, as this will be a frequent task.
