I know we can increase the map size (height or width), but has anyone managed to reduce it ?

I'm working on the map for the Viking Age : Total War, and we are planning to have a 220*260 map.
Since our map was 255*260, I had to delete all provinces in the east (Tribus Sakae, Atropatene, Media; Babylonia, Elymais, Arabia) and edit a few others (Armenia, Tribus Alani, Colchis, Assyria, Regnum Palmyrae and Nabataea).
I either deleted all the entries in descr_strat that went farther than 220 (ressources, babylon garden) or changed their coordinates (armies, agents), thanks to -show_err.
I 've edited the descr_terrain file, and all the tga files that had to be edited (Features, Region of course, Trade roads, Height, Ground Type, Roughness).

At first sight, everything looks fine, but when I tried to launch the campaign, it CTDed

Does anyone have any clue about what I'm supposed to do, or what I've screwed up ?