Stateful Set in Kubernetes is specifically designed for stateful application, and it works well with Confluence Data Center.
This is how I designed to run Confluence Data Center on Kubernetes (AWS EKS).
And here is a quick demo of scaling up and down.
Jackie Chen's IT Workshop 
Do you have your chart published somewhere? It would be nice to see how you actually put this together rather than just screen captures/videos.
Yes I am interested too