Internally it is necessary to do additional DNS work:
So what would the guidance be setting up SharePoint Hosted App using a reverse proxy; would this require split-brain for each App?
My head hurts thinking about it.
A split DNS solution would be required for external access in some on-prem topologies. But not for each app, as you would rely on a single wildcard DNS records and not on individual records.
Here is a blog post that explains this scenario in a bit more:
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