I wonder if there is some way to play these battles against another player (of course in such case you would have to wait until this player is also online). That's why usually people play with 'all battles auto-resolved' in Hotseat campaigns.
When you attack an army of another faction which is human-controlled, AI controls this guys' army on the battlefield. One shortcoming is that you can't actually fight battles against other players. It is still more chalenging than playing against AI.
If you play with all factions controlled by humans, you wait many days for your turn but it doesn't matter. Hotseat campaigns in M2TW are pretty fun.
