jareware
I do the same, and have spent some time automating the backup of such a set of standalone containers [0], in case others also find it useful.
Just pipe curl to node (https://github.com/jareware/howto/blob/master/Replacing%20jq...) or Python or Ruby or whatever you already know!
Instead, it allows you to use the same tool and management model for resources on any of the 3 big cloud providers, about a 100 assorted SaaS providers, and most importantly, wire them together (e.g. create a Mailgun configuration, and set up its verification DNS records on AWS), all in code, and in the same workflow.
It effectively automates the process that's described in the article. Once you have it set up (you need a few DNS entries and a tiny Go server running somewhere), using it is as simple as issuing an HTTP API call to your alley-oop server with the LAN IP you have, and the DynDNS domain you want associated with it, and getting a valid cert in return. You're then ready to spin up your HTTPS server with it, and start serving LAN traffic with a valid cert.