I'm not really plugged into this world any more, but I'm not aware of any serious singlehand races oriented towards traditional cruising boats like your Rafiki. Nowadays they tend to be organized for all out racers, all the way from the Mini Transat to the Open 60's of the BOC (or whatever the hell they call that race
On a somewhat less extreme level, the Singlehand Sailing Society in SF Bay
runs a number of inshore races each year, plus the Singlehand Transpac every other year. They use (IIRC) PHRF ratings, and there are boats of all descriptions entered. They have a website, and I would recommend that you peruse it... if you haven't already done so. I've been out of the SH racing
scene for over twenty years (oops. make that thirty years!), but still remember how rewarding it was for me. So, good luck with your efforts.