Put down militia and fortifications. The losses a landing army suffers if it faces any kind of serious defense are devastating. There's your balance - your enemy is as blind as you are.
It's not that hard to coordinate a land and sea army where the land army destroys the militia, starts a TO and is then guarded from intervention by the threat of a out of the blue reinforcement by sea. I don't mind at all that they /can/ be reinforced so easily, the only issue I have is that it is nigh impossible to know anything about the reinforcements until they've already arrived. Making battles not a thing of planning, but just of stabbing in the dark. The only way to cope with it would be late-turn movements and I don't think that's something to be encouraged.
