Air-Gap-Systems: Running with private docker registry?

Hello All,
We air-gap our systems to make sure that everything is scanned for insecure images and other potential problems. If the systems are pulling from our internal repo they don't need to authenticate. It appears though that there is no way to change where the images are pulled from at a hostname level. So this means we can't use the ECK correct? Seems like an easily fixable problem. Plus you can also set the authentication at the Docker on the host/node level so that wouldn't require imagePullSecrets.

Am I correct? Is there no way to use any other Repo?
Thanks,
Brian