Yes, that's an option. However, you must realize two things:
1) This will require people to have at least some of the BOS files unpacked. Only modders/mappers usually have this done. The average person is going to need help doing it, so you'll have to include instructions in your ReadMe.
2) Unless you're going to include instructions on how to use the -path command and settting up a mirrored directory you're asking people to over-write their core campaign to play your mod. How many people will want to do that?
Don't get me wrong, starting in a bunker is a good idea as it gives the player the maximum number of choices possible. I'm doing the exact same thing in my SP campaign and had to go through some serious scripting voodoo to get it working correctly, but it's something that I felt should have been done originally, so I did it.
OTB