See also references:
* https://www.digitalocean.com/community/questions/how-to-support-internal-traffic-with-proxy-protocol-enabled-on-a-kubernetes-loadbalancer
* https://github.com/digitalocean/digitalocean-cloud-controller-manager/blob/master/docs/controllers/services/examples/README.md#accessing-pods-over-a-managed-load-balancer-from-inside-the-cluster
* https://github.com/kubernetes/kubernetes/issues/66607
* https://github.com/compumike/hairpin-proxy

I think it's worth adding a feature in the nginx rather than introducing a batch of workarounds.