It's finally finished! My kitchener stitch attempts were likely just too tight, but I decided to work the join from the other side and it looks perfect!
The shawl pattern is Air by Erica Jackofsky, part of an elements collection. It was a mystery knit along, I bought my yarn before the pattern was released, but didn't start knitting until all the parts were released so I did know what it was going to look like and how to work my color change/gradient before starting.
I do still need to weave in my ends (I hid them for these pictures), but I'm finally finished!