The problem with a strong player as France is that it has the potential to completely wreck the game for everyone else. If the French player can hold the line then what does the German player do? It is GG by '40. On the other-hand, I wonder if the Carnage folks would amend the rules for an allies vs commies game, that would be very interesting.
It would be interesting to see a Pacific war between a US Cpt and a Japanese Zid, although it is always fun to watch Cpt pull rabbits out of hats on a shoe-string budget.
As to the games of Cpt as UK see Jolly Carnage
And Cpt as USSR see Sudden Patriotic Carnage