Best way to deploy EV

Hi

We have two sites, UK and US

2 Node Exchange 2010 DAG running in UK and US.

UK users have mailboxes in UK Node DB and US users have mailboxes in US Node DB, we have passive copied of both DB in both locations.

around 200 mailboxes in each UK and US Node

Both Nodes are CAS and HUB server as well. So need EV OWA for both sites.

What is the best way to deploy EV in this scenario? Main EV directory server in one location and then 2nd EV storage server in other location? The directory traffic will be routed via WAN link?

Thanks in advance for your help.