I'm looking for a way to serve a "Maintenance Mode" website from Amazon S3 or Azure Blob storage while I'm updating my website to a new version. I'd like to just flip DNS over to point to maint.mydomain.com (which would be a static site & return 503 http status). Is this possible to do with either of these, or would I need to create a traditional website to host this?

I can get S3 to serve a website, but it always shows HTTP status 200. Any ideas?