Has any great person here written a Back up / DR for Splunk ES? Any guidance is much appreciated.

[SamHTexas]

I have Indexer clustering, SH clustering in a distributed environment. 

[lkutch_splunk]

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. 

[codebuilder]

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.

https://docs.splunk.com/Documentation/Splunk/8.2.1/Indexer/Multisitearchitecture