Since you already have to deploy the contact form handler, you might as well have that same program deal with ssl and serve your static assets.
For LetsEncrypt, start with this autocert example, but make sure and add a cache so that when your program restarts it doesn’t have to replace certs that aren’t expired yet.
To serve your static assets, start with this file server example.
I run my site, https://pocketgophers.com in a similar way and described my deployment in another thread. This post describes things like graceful restarts, process management, and git push to deploy.