Caddy as "acme forward proxy"?

[matt (Matt Holt)]

I would use the DNS challenge so that you do not need to worry about an ACME server trying to reach your server:

How to use DNS provider modules in Caddy 2

Caddy 2 uses a new and improved DNS provider interface for solving the ACME DNS challenge. All you have to do is plug the service provider(s) you need into your build, then add the DNS challenge to your configuration! Getting a DNS provider plugin How you choose to get a custom Caddy build is up to you; we’ll describe two common methods here. Method 1: Go to the Caddy download page. Find your DNS provider in the list of modules (dns.providers.*) and select it. Download your custom Caddy …

Much simpler.