an idea for possibly giving hints to bases without giving it away, is to have a Dynamic Map.
That doesn't show player locations or the map itself but shows a 10x10 grid (each grid consisting of 1000x1000 blocks) which changes colors based on activity (Amount of people, blocks placed or Deleted, Mobs/players killed)
it would go from Green (Little/No Activity) to Red (High Activity)
This allows for people to know how much activity in each grid of the aggression map, without knowing precisely whats going on. Encouraging exploration, and discouraging factions from being too hidey
Maybe allow reporting of faction locations, which factions' names will appear on the map in the grid the report was given in.