Hi,
Yes, Splunk can be integrated with anything.
I've integrated it with Campaign in fully hosted and on-prem deployments, usually writing simple python scripts that make soap calls to the instances. To do this: find out from your client what kpi's they're interested in and their language preference, then write the xtk:querydef calls for them, e.g. a specific set of workflows need to not be in an error state, unsub rates for deliveries shouldn't exceed 10%, etc.
Thanks,
-Jon