Well, maybe it's not 'racey' or something.. and I would certainly use proper small stuff.. but your technique there should work just fine. Maybe a couple of vertical turns between the sail and the stay, just to keep plenty of tension in the system (will help keep the sail from sliding up/down the stay, as well as keep the knot from shaking out).
I don't know.. I mean, spend money if you want. But that will work fine (though the choice of small stuff is not something to ignore.. what are you using now?)
... or I'm wrong.
Living aboard, currently in the Chesapeake
O'Day 37, still new to us