But that doesn't disable the map contact update, does it ?

I disabled those in the realism settings but still get a small icon displayed on the nav map when zoomed in for every ship my crew is able to spot.
This also gives away my own position - roughly, but still.

Your sub small dot dissapears.. It's what I'm currently using.

I set no map updates, etc.. in career mode and I only see the little square box for either a ship or a task force when a message appears, otherwise nothing else.

You might have to explore the mods and pull out what you need.
The mod readme files have all the info.

:D