Aren't these figures in early war uniform?
Since you will only be doing alternative crews in metal, could you provide the basic crew with later uniforms, without jackboots? They could then be painted for North Africa, Mediterranean, Norman and Russia.
These poses seem rather static too. There's no urgency in their movement - they look like they are on an exercise. Rather like the older Tamiya poses. There should be at least one covering his ears, and someone pulling a round out of an ammo container.
