Come and get me!
IMO for simplicity's sake, have each country hold qualifier rounds from which the four best pilots will emerge (And backups for when real life takes precedence), and then from a random draw pit two different country teams together, have them climb a ladder this way until the finals.
And for those countries who have just too many pilots, use the division idea. The points don't add to those of the team competing for the world cup, but they still can be crowned winners of their division, with say an honourable mention.