I've pinpointed a problem - newbie landless knights have nothing to do in stagnant realms. I'm trying to find a solution. This is basically just brainstorming so far.
This is good to do. However, this particular idea is not, I think, a helpful one.
Most knights aren't going to want to use a mechanic that is inherently designed to be disruptive to the political status quo. Those who do are likely to get themselves banned double-quick. And if we make it so it's difficult or impossible for the higher-ups within the realm to detect, that's just going to cause all kinds of anger and frustration, and rightly so. (And if we make it impossible for people on either side to detect, it's just going to fail to cause any kind of political disruption
and make the people in the other realm really, really mad when they find out that some of their border regions are mysteriously in crap shape!)
When doing your brainstorming, keep this in mind, Constantine: Most knights, especially those who are likely to stay knights their entire time in the game, don't want to be causing trouble. They want options that will let them help their realm, not screw things up for it.