I think this is a great idea. I think it should be limited to North America (at least to start, or else they might be spread too thinly; maybe someone could use this model to start a game in other places).
What would the teams be? East vs. West pops into mind first, but North vs. South could be cool, too. They should be color-coded, I think. You would probably have to buy TBs in bulk.
I would start by deploying a bunch of soldiers to the proper locations and stick a "flag" in a centralized cache. Whichever gets to that cache first wins. Afterwords, you could post a variety of missions for the soldiers to accomplish based on the positions of other soldiers (for example, several soldiers in a cache could be POWs that need rescuing). You could either act as a general and assign missions or just let people choose which one they want a soldier to pursue.
I think your idea is really cool and I'd love to help out if I can. I hope my suggestions are useful, too.