Write override-config.yml to reverse proxy domain path to cloud service with nginx-proxy-automation?

Question

I am using https://github.com/evertramos/nginx-proxy-automation/ and it has as a component https://github.com/nginx-proxy/docker-gen.

I would like to proxy a location on my host https://someurl.com/consumer -> https://project_id.cloudfunctions.net

In a non-docker setup I would write something like so in a someurl_com.conf file:

server {
    listen 443 ssl;
    server_name someurl'.com;

    ssl_certificate /path/to/certificate;
    ssl_certificate_key /path/to/key;

    location /consumer {
        proxy_pass https://project_id.cloudfunctions.net/;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        underscores_in_headers on;
        proxy_set_header proxy_ssl_server_name $host;
    }
}

I am trying to figure out what I would put in the compose-override.yml file to cause the proper configuration to be generated by nginx-proxy-automation-gen's nginx.tmpl but not have it interfere with other proxied sites.

services:
  nginx-proxy-automation-cfproject_id:
    environment:
      VIRTUAL_HOST: "someurl.com"
      VIRTUAL_PORT: "443"

However, docker requires an image and this where things get weird, docker requires each service to have an image. At first my thought was to attach a generic alpine container, but it seems like wasteful and insecure way to go about this.

Is there best practice method to work around this?