Gitlab what should base domain for ingress be if more than 1 cluster?

I have two clusters. My gitlab is gitlab ee 13.2.2

One where the environment is set to staging and one where it is production.

When I just had one cluster for the base domain I entered the domain I was using for a subdomain to access my gitlab via: gitlab.mydomain.com

So in my domain provider I set *.mydomain.com to the IP that the ingress provided me.

Now that I have an extra cluster (for staging) I am unsure what to enter for the base domain and in the domain provider what to enter (*.staging.mydomain.com?)

I am also assuming for my projects that have their own domains, that I can just point their domain provider to the ingress IP for each ingress like:

*.projectdomain.com = cluster1-ingress-production-ip

and

*.staging.projectdomain.com = cluster2-ingress-staging-ip 

In the gitlab-ci for staging it would be like:

deploy_review:
  image:
    name: lachlanevenson/k8s-kubectl:latest
    entrypoint: ["/bin/sh", "-c"]
  stage: review
  only:
    - branches
  except:
    - tags
  environment:
    name: staging
    url: https://$CI_ENVIRONMENT_SLUG.projectdomain.com
    on_stop: stop_review

In the gitlab-ci for production it would be something like:

deploy:
  image:
    name: lachlanevenson/k8s-kubectl:latest
    entrypoint: ["/bin/sh", "-c"]
  stage: deploy
  environment:
    name: production
    url: https://projectdomain.com/