Hi Chris, you may want to read though my on going thread, I have a very simular issue and have almost identical Use case that you do.
I have no answers yet, I also came across this other page
Logstash Indexer to Elastcsearch Tunnings ( must go faster!)
Here is the link
Under Integrations
https://www.elastic.co/guide/en/elasticsearch/plugins/2.3/integrations.html
Here is the product
https://github.com/reachkrishnaraj/kafka-elasticsearch-standalone-consumer/tree/branch2.0