Hi, I had read a bit about the worldmap and the players, but still need more info about ...
Anyway I have think about 2 way to make CvC on the worldmap :
I) Clan War with the both clans in the same map (when the War start, all enemys is add to your map).
II) Clan War with a part of the map than let you move your army to the enemy's map, in a safe zone (no enemy's units or city).
Something like this :