I made one before, but making one again. WTF ZoS was you thinking with the low population bonus. This needs to be removed when the new gear comes out and the campaign rewards are actually meaningful :
Its a never ending battle you have players who will funnel to where ever they want to funnel and that's the sad case you have Euro players on Na servers and Na player son EU servers so you cant stop that, Only option I see and I mentioned it 2 years ago it to have the servers open from XXX time to XX time and then others open to offset this..in the mean time having these servers on 12 hrs off 12 hrs also leads to them able to do daily maintenance on severs as well.
OR you just flatly make the campaigns 2 weeks or 30 days and narrow them down till there all pop locked