For us we are using WAN compression and tweak the settings in the client config.
I am vary wary of attempting to install a client machine over the WAN though. Typically I do it piecemeal. I run the client installer then grab a copy of the client folder from a machine in the same network and copy it over.
When we first implemented our intention was to use Epicor Web Access for all of our remote sites, but its performance was worse than the rich client over the WAN.
Cheers
Simon Hall