Let’s face it. 90% of the reason most won’t just reroll… they got a good name. If you reroll on a new server, chances are you won’t get your name again.
Create 2 new servers, one for each overpopulated one. And, allow ONLY transfers from one to the others sister server.
Only Whitemane can transfer to Whitemane2.
This is really the only solution I see, that would work.