I understand that Nostalrius' team is looking to create a truly near-authentic experience, and so I'm here to propose something to ensure that.
I'm proposing that the staff prevent players from owning characters of both factions on the same IP.
This might not completely eradicate cross-faction, but it should deter a large bulk of players from engaging in cross-faction activities.
On a retail server, people wouldn't be able to make characters on both factions on the same realm, and unfortunately some additional measures have to be taken to make certain that this is the case on a private server.
Spying on other players to hunt them down, and communicating cross-faction, and various other advantages deteriorates faction versus faction gameplay, and damages the integrity of many of the game's aspects.
If people want to change factions, then maybe they can arrange with the developers to lock their current faction's account to begin the opposite faction one. Maybe it could be automated somehow.
I think that these restrictions should only apply if a person owns at least one level 60 character.