Ben,
So there can be an "official" plain text version in that it
is on the RFC Editor's website, but it is not authoritative or immutable.
There already is an official plain text rendering on the RFC Editor's website. See, for example, https://www.rfc-editor.org/rfc/rfc8905.txt, and https://www.rfc-editor.org/info/rfc8905, which has the button to press to get it.
That said, the plain text version is the least useful rendering for reading, since it can't include any SVG drawings. It's really only useful as input to rfcdiff. If you want to read on a screen, use the HTML rendering, and if you want to print it, use the PDF rendering.
Cheers,
Andy
