I too am looking for this. We had it at one time. Paper Map w/Height allowed this. If you followed the simple instructions to zero out the Z axis it essentially removes all of the markers. Sadly, the mod was abandoned and thus suffered incompatibilities with patch 1.8 and shut it down. Others have taken up the project and the most recent being Warbugs 3D Paper Map but he says he tried to make it flat and it's impossible. Not sure how that is exactly, but that's the word. Maybe someone can take the original meshes and textures and incorporate them to work with the current patch. That would solve everything.