And as another comment mentions, GitHub Pages now offers HTTPS certificates [1] for custom domains, so GitHub Pages alone is sufficient for most static websites.
[1]: https://github.blog/2018-05-01-github-pages-custom-domains-h...
IMO the simplest solution for the OP is to have a private repository where he does any draft work, and then pushes the master branch (or whatever) to the public repo in order to "publish".
This option is available with or without a paid account, and I don't see any significantly better option available to paid accounts. The only thing you could do there is publish your pages from a private repo, and maintain your drafts in branches in the same repo. That is virtually identical to the original suggestion except that "master branch in public repo" is replaced by "master branch in private (same) repo" which probably makes little practical difference in the workflow.