I have Indexer clustering, SH clustering in a distributed environment.
For the ES portion of things, also consider this:https://docs.splunk.com/Documentation/ES/6.6.0/Install/InstallEnterpriseSecuritySHC#Back_up_and_rest...
Let me know if that helps.
This is a complex topic and you should really engage Splunk support for guidance on how to implement these strategies.
With that said, one option for DR is to implement multi-site clustering.