oh good point about the different world generator settings - looking at it right now I see both checkbox selections to include/exclude only the spawns I want to see, and dropdown to show Full Terrain, Biomes Only, or No Terrain (Fog)

Sounds like if I only check Haldor box, and select No Terrain, I will have an unrevealed map but show generally where in world Haldor spawn locs are.

Will give that a try.