ZOS give all EP characters 1 FREE faction change token.Make it a Nord festival activity. One time use and it can only be used by that EP character. The character would have to go to the starting zone city and talk to some character at the festival that you come up with and then they could use it for a limited time while the festival is active, like a week or something. If they don't use it then it would be gone.
It would help with the pop imbalance. Nothing against EP players. I have a few EP characters myself from back in the day. This festival could happen annually like all the other seasonal festivals, but it would switch to whatever the overpop faction is at that time. Obviously this would be for the main CP campaign.