I at first assumed this was already the case, but now I'm less sure of myself. (Other games always have some kind of "watchtower-like" building, and Illyriad does not, but has scouts, so this is what I first thought was one of their defensive functions.)
Does the presence of defensive/idle scouts impact the reporting of incoming military attacks? i.e. have the chance of seeing troop counts be proportional to the number of defending scouts at home/camp (when the latter exists and supports non-military presence)--also inversely proportional to the distance of the attackers. The in-game attack details could withhold that information until such a proximity is reached. If this is not the current behavior, could it be, pretty please?
This would function very similarly to typical watchtower behavior, with the twist that scouts can spread out and fewer are required to accurately assess smaller groups, so small attacks would be identified sooner/from much further away. Realism is satisfied and as a bonus feints will have to commit sizeable forces to be taken seriously. Feints are a useful tactic, so they shouldn't be cheap.
Sending meaningful amounts of force away from home for a while satisfies this.
I believe this would also fit well with other discussions regarding diplomatic units. How many scouts one chooses to employ would depend upon which considerations are being more highly valued.