heres an idea, not saying its best, but its different -

Rather than 2 teams of 4 in a race, have 4 teams of 2. Nations with fewer players can then get involved.

Play a few tornies over x number of weeks, and the top 2 teams go through.

Nations with bigger numbers are split into teams of 2, and placed in the same group, guarenteeing only half will qualify from round 1 ( another way would be creating the 2 teams AT THE END of round 1 based on the top 4 positions - pos.1 & pos.2, pos.3 & pos.4 ).

this is the only method i could think of to include every player in every race, and to include rivalries wthin nations