Right, it looks like the best way to form the teams would be to do North America v Rest of the World. So NAFTA v ROTW. And this is how the tournament would work, broadly speaking:
1) 2 teams, Team NAFTA and Team ROTW
2) 12 players per team;
3) each team nominates a captain;
4) the two captains select the 12 players, which will include themselves;
5) the 2 teams are split in 2 sub teams of 6 players each based on their 1v1 GR at the end of September 17; these teams will be called NAFTA-1 and NAFTA-2 and ROTW-1 and ROTW-2 respectively; therefore the strongest 6 players will form NAFTA-1 and ROTW-1;
6) the 6 player teams will be further split into 2 sub teams based on their country preference (to be decided by the respective captains), ie NAFTA-1A; NAFTA-1F; NAFTA-2A; NAFTA-2F and the same for ROTW;
7) NAFTA-1 will play 6 matches (2 games each, 1 France and 1 Austria) against ROTW-1. The pairing will be random. NAFTA-2 will play ROTW-2 the same way. These games will be 24h;
8) After the completion of the above 12 'Singles' there will be 6 further matches - the 'Doubles'. NAFTA-1A will play together with NAFTA-2F 3 matches against ROTW-1A and ROTW-2F whereby the 'A' players will play a single game with austria and their team mates 'F' will play France in the same match; these games will also be 24h;
9) finally, in parallel with the first 12 'Singles' a single 'Team' match will be played - the 'F' players will play together a single game playing France and their 'A' team mates will play a single game playing Austria. A captain for each subteam will be nominated and that would be the person to enter the orders (for the purpose a new profile can be created so not to affect the GR). Given the comms within a team required to agree a set of orders this single game will be on 48h.
10) the total number of matches played will therefore be 19. Each win scores a point, a draw 1/2 and a loss 0, with the exception of the 'Team' match which will score double, ie 2 points for a win, 1 for a draw and 0 for a loss.
11) the total number of points available will therefore be 20. The team that scores 10.5 points or more is the winner.
12) timescales wise the 12 'Singles' and the 'Team' match will start at the same time but the former will end much sooner. The 6 doubles will commence 2 weeks after so that most of the singles will be over by then. Chances are the 'Team' game will end more or less at the same time as the doubles.