To answer the original question regarding navigation in CFS3:
No, can't be done accurately.
CFS 3, unlike it's other MS sisters, uses a flat map as opposed to a round world, thus real world coordinates are stretched and distorted.
This has been done to simplify the underlaying math for gunnery, esspecially for moving guns. It's just easier to calculate a bullet path in a square box than on a round surface.
The price for having manneable gunner stations, if you will.
This is also the reason why there is a map size limit in CFS3.