I dont think many mods change the default maps. most mods dont even have new maps. if youre desparate for changing them then you can either:
a) change the name of the default map's texture (located in Soldat\Textures\texturename.bmp). Use like map maker or ask somone if youre not sure which of the textures that map uses.
b) use
PolyWorks to open the default map you wanna change the texture to, go to Edit > Map Settings (or just do CTRL + M), click the dropdown box next to the picture of the texture, and select the next texture you wanted it to be. find whichever one you like, then hit OK, then File > Save As... and add like v2 to the end of it so you still have the original map too.
hope that helps!