You could fake this by making a MP mission, but intended for only one player. With some fancy scripting you could probably make the mission exit if two humans attempted to play it as a co-op.
If you wanted to keep it SP, making the player start in different places or different groups is straightforward. You could certainly start with the mission a dialogue which setPossed the player to a particular place depending on his choices. However, the hard bit would be his clothes - you're pretty much stuck with one player unit which means one outfit. Again, you could perhaps fake it by making a fake campaign: one input to the dialogue runs the mission, the other ends the mission and starts the next mission inthe campaign, which is in fact the same mission but played from a different perspective.
Nice idea, hope you can make it work. Whatever you do, it's going to be sophisticated. I recommend you make the basic mission first - say with an infantryman player - and once it's finished, start on this problem.