The next idea is about exploring the map. The normal AoK's system is clear, if your move your unit, it leaves a trail of explored land behind it-self which is then covered in fog of war if there's no unit around.
If my scout moves too far from last settlement (let's say 512 tiles far) he won't leave any FoW trail anymore until he safely returns. Then his path will reveal the explored land he scouted. If he dies the exploration dies with him. So when sending scout on long journeys give him a supply cart or some gold and hope he will find some village to buy food.
If you find out you were scouted you can send cavalery after the spy and secure your location stays secret. Or if you know the spy left west and there is only one bridge on the river west, you can wait for him there.