I also maintained several kubernetes clusters and never found it very difficult. We never had any major outages, and the only downtime was trying new features.
What's the scale of your clusters? If you're running anywhere between 5 - 20 nodes with a 10 pods on each node. I think that's a very small deployment and you'll be able to breeze by with most of the defaults. You still need to configure the following though - logs, certificates, authentication, authorization, os upgrades, kubernetes upgrades, etc.
I'm not sure if all of this is worth it, if you're running a small footprint. You're better of using more managed solutions available today.
