I didn't know RFCs are being written with xml2rfc directly anymore; I was under the impression most work was now happening through https://github.com/cabo/kramdown-rfc, which lets you hand-write markdown instead of hand-writing XML.
And then https://github.com/martinthomson/i-d-template, though a bit elaborate, does automate a lot of IETF stuff, including use of kramdown-rfc.