If anyone is interested, I've started maintaining a docker ghost base image that has built in S3 and GCS support: https://github.com/OSAlt/gb-docker-ghost #opensource #ghost.
If you're not familiar ghost is a very nice and simple CMS. You can read more about it here.
Addendum:
GCS has a bug when resolving the favicon, I got around that by adding the following snippet in the nginx server configuration.
location /favicon.png {
alias /var/www/html/ghost/favicon.png;
allow all;
}
Naturally this is no longer configurable via the CMS but at least it doesn't end up with an internal server error which is the current behavior.