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.

5 clusters of around 100 nodes each on average