I’m still wondering why you think more is necessary than the READONLY mechanism from the OP.. If that doesn’t work, my tweak to Mohammad’s tool might be helpful. It’s designed around my own workflow, where I use Node for development and single-file (GH pages, elsewhere) for deployment. But you can also use it with single-file only, so long as you’re willing to use a keystroke (CMD/CTRL-SHIFT-/ or CMD/CTRL-SHIFT-1) to toggle between read-only and edit modes, and to remember to turn off edit mode before deploying. (You might need a bookmarklet to save in this configuration; if you need it I can probably help develop one.)
If you want some of the print stylesheet tweaks suggested, by all means include them. One easy one would be @media print {.tc-story-river {display: none;}}, assuming you’re using the story river for your content..
As to preventing downloads, I still think you’re trying the impossible. Here’s the link from the OP again:
Right-click that link, and choose something like “Save link as…” and you’ll get your very own copy of that document. I don’t know how you would share your work without something similar. And this is before your tool even loads.