Add all teammates must accept surrender; make it on by default. Allow backup players: if player is booted/ surrenders, he gets replaced by backup, not AI. Allow adding extra card pieces for certain slots in multiplayer. Allow adding extra card pieces for territories in manual custom scenario.
That would be nice but the AI is belt in a way that even the toughest player have a hard time against because the AI goes for neutral territories, places 1 troop in most of its territories surrounding the player and of course one massive dump to destroy the other guy. if the difficulty was changed, so would the AI we all know