That is actually a very good idea.
Something like:
Hostile Terrain Specialists:
When creating your Company, choose one of the following terrains: Jungle, Desert, Ice, Swamps, Mountains, Subterranean, Submarine, Void, Toxic/Irradiated.
When fighting or maneuvering in the chosen terrain, tell how you use it in your advantage and your Company rolls with Advantage. Your officers can always give you an idea of the potential threats in an area of that type.