What about having an option for a fake fog of war? Only have the mini-map set at a specic zoom and you can't zoom in or out. The level could be specified in the ini file. Then just have an overlay that has a central circle of visibility with black all around that. Maybe double the distance you can see if someone is playing in third person mode, though of course that too would be configurable. I play in 1st person and it would be nice having the map just to get my local bearings.

Other (good) news, I'm working on an OBSE plugin which will enable me to add map markers to the MiniMap. And possible quest markers aswell, although only for the world MiniMap.