Have you made any progress on this? Could you share your experience since posting?
We are adding a remote site that will generate a lot of publishing and I know you can configure Distributed File Server Workers for Pro/E-Creo to publish at remote sites to avoid the WAN transfer, but I haven't tried it - http://support.ptc.com/cs/help/windchill_hc/wc100_hc/index.jspx?id=ConfigDistributeFileServerWorkIntro&action=show.
I'm also wondering if you have any master vaults at remote sites. We currently only have one master vault at the master site, but I think you can create a master vault on any site. It would probably make sense to do that if most of the data generated at a particular site will only be used there. Any experience with that?