Hyper-V replication across the WAN

I've recently been working on Hyper-V replication across the Internet to give our clients the option of maintaining an offsite copy of their server in our data center. Everything was going smoothly up to a point. I set up a site-to-site VPN connection between them and us, built an Active Directory two way trust between their domain and ours, and then tried to enter their Hyper-V host into our System Center Virtual Machine Manager system.  This is where I ran into a road block.

Every time I tried to run through the wizard to add the client's hyper-v host in, it would come back with an error 415, agent installation failed copying. SCVMM was trying to copy it's agent installer to the $ADMIN share on the Hyper-V host and was unable to. Everything I read online while troubleshooting this said it was authentication, and since I've never had this problem before while working with hosts that were on the same domain as the SCVMM server, this seemed like the logical place to look. But nothing I did in this regard made any difference.

Finally out of desperation, I checked the roles and features installed on the client's Hyper-V host. And sure enough, after adding File and Storage Services/File and iSCSI Services/File Server under roles on the host (it shouldn't be too hard to find, Hyper-V server doesn't have a lot of choices under roles), I was then able to add the machine into SCVMM and proceed.  From there I was able to set up Hyper-V replication with one of my Hyper-V test beds (we're still in the proof of concept phase, no need taking up disk space on our SAN yet) and away it went. The virtual server had about 61GB in VHDs, and the initial replication took a hair over 12 hours.  Not too shabby for a dry run through a proof of concept setup.