To graft that final knit-purl pair, start with “wrong” side facing:
- plunge a blunt tapestry needle into the base of the final stitch
- leaving needle in place, pull tail up and out
- poke eye of tapestry needle from purl side to knit side of penultimate stitch
- thread tail in eye of tapestry needle
- pull needle to bring tail through penultimate stitch and to re-complete final stitch.
I prefer to duplicate stitch ends. In this case, I don't have any horizontal fabric that I can use for duplicate stitch. Plan B is hiding the ends vertically. Identify a knit wale and thread the tail down through a vertical column of stitch legs. This isn't my favorite way to deal with an end, but it will work in a pinch.