Apart from having a single DCR for all servers I don't think there is much that can be done.
Question is, do you need any local management when the WAN is down.
If not, you can manage all devices from one remote server. The management traffic is no big deal for nowadays WAN.
I believe you could also just have the DFM module on one server in Manchester and have local servers that have RME, CAMPUS and the other modules.
I don't think you can get the DFM alerts from multiple servers togehter in one view
If I read the cisco marketing it says that LMS is able to "understand" that a given tool for device X runs on RME@server3 where for device Y the same tool runs on RME@server2.
I have however not yet tried such a thing.
I guess you need a statement from you cisco account manager that this works and has been tested
Cheers,
Michel