[DogEater]

I mentioned the snow with the thought that a winter map may make a better base for the mod, but use your green texture.

I got a black wall on the water with sands of time too

Snow map will be good idea, because lightess settings of the ground may be without that stains (you can see it at the last screen).
Could you create new map_h.tga same "bowl" type for empty1a or empty1b? We need texture size for that small maps.
Another advantage of small map: angle of view will be larger at the small map rather the big map with same height of border walls.
Do you know about maximum height of the lanscape in game engine? The 3000 meters height - is it a limit or just your example?