In the editor, place your crosshair in the very top right of the map with it zoomed in. On the bottom, it should tell you some coordinates, that is the map size. I think all the maps are square, but if not, just use the larger number (x or y).
For example, Takistan, I believe, has a map size of 12800.
I am having a different problem, since the update, the insurgency module is no longer spawning enemies. The mission was unchanged, and was working prior to the update. I even tried loading the example mission that comes with XLib, and no enemies were spawning. Is anyone else having this problem?