Are you sure this is needed in any way? I mean at this point we know almost nothing about how the game will play and what variables will be in place.
Also It does strike me that you would need some rather good mappers for this, hell we don't even know how well mapping will be accommodated, so I'd suggest holding your horses for now.
Good luck with the administration when the time comes, if previous attempts at similar campaigns can tell you anything it is that you're going to need it.
Some words of advice:
- Taking the entire country will take way too long, center around a smaller series of conflicts instead, less room for unforeseen screw ups that way.
- Cherry pick who will attend with great care, you don't want months of preparation screwed by individuals who bite off more than they can chew.
- Have a lot of backup administrators, and people helping you in general, there must always be someone to fill someone elses shoes in case of unforeseen circumstances.
There is so much that could go wrong with this no matter how much blood and sweat you pour into this, don't make the decision to manage something like this lightly.
If you're still convinced that you want the campaign to span the entirety of the country then I recommend that you break it up into smaller sets of engagements instead, where you make each set have absolutely no relevance to the previous set, having people reapply for each and so forth. Essentially making each set a separate event in their own right.