With the set up we have I would have victory conditions as follows:
There are 20 Capitals in the game. You should need 10 to win (and hold them for 3 turns). But you need at least one Capital from two different (none AI) teams. And your own Capitals only count if they are held by their original power (AI or not). So if you lose a team Capital you can take it back / gift it back to the original player and it still counts. But if that player has been eliminated or for what ever reason does not hold his Capital, even if his team does, that one does not count and they need an extra capital from somewhere else.
That should ensure that the teams try to keep everyone in, but doesn't cripple them if one or more are lost.
As I am not one of those players who likes to play on and on and on and on just for the sake of it. I would also allow concessions if there is a an obvious winner. Let say that if
all the other Team captains (the Vets) agree then a winning team can be declared before this.
Re whether I play or mod the map. I would prefer to play as I like team games
But if you can't find anyone else I will step down and mod the map.