Ask HN: How to Setup Cloudflare DNS Proxy and GCP Load Balancer with HTTPS?

I have Cloudflare DNS Proxy connect to my GCP load balancer API endpoint via HTTPS with a signed google certificate. The load balancer has a firewall rule allowing only Cloudflare IPs to connect. Once every 3 months in order to update the google certificate I need to disable the firewall rule and turn off the DNS proxy. A manual process that lowers my security.

Is there a better approach to this?