I’m playing on a private server that has this set up, when you leave EL your character is copied to Siptah.
The EL copy is deleted, then the opposite happens when you port back to EL.
I’ve gone back and forth a few times, and it’s awesome.
All it would require is two linked servers and a device to activate the transfer.
The server I’m on uses the model of the activation stone like on the Map Room.