Mesh based on EoIP. I get 100%CPU and 100% load on EoIP

You don’t need to do anything special. WiFi roaming is a function of client, not AP. I recommend reading a couple of great posts on the topic: first, second.

And I do not recommend kicking off clients based on signal strength to force them roam- this usually makes roaming experience worse.

From my experience, the best roaming results can be achieved when using CAPsMAN with local forwarding turned off.