Well this solution came my mind
http://i35.tinypic.com/28svi11.pngIt might feel lame, but it really isn't. I think it's also very pointless trying to make first one half and then trying to make the other half similiar (for example Voland). It just makes the work hard for u. If you are doing a lot more different other half (like nuubia), then its reasonable making it without mirroring. Next example from between these examples: If I would remake Laos from start, in that case I would make half ready, mirror it and then start moving polys.
I'm not saying that I recommend making mirrored maps. When map is small, it's better to be mirrored cos there small differences make bigger advantages than in bigger maps.
At this case I would recommend the Laos method: Mirroring it and after mirroring, making sides different by moving polys.