You can't do this with CK2 engine.
For instance the armies on the map would not be mirrored.
You could put straits at the end of eache side of the map
I'm no map modder, so if one reads this please correct me if I'm wrong, but I would say yes
I'm not the best one when it comes to map modding, but technically, it should work yes. Just add a province in Eastern Siberia and another in Alaska, and add the strait. Same thing for sea zones, just add a portage between then. Though you'd have to adjust the height so they don't show up on the map (ie. they should be under the terrain and the sea).
You can't.Thanks but i don't understand how can do