I suppose I could use a solid piece of wire and use a short piece of shrink tube so sail doesn’t get poked by wire??
Hmmm, not seeing a slot in the spreader tip. But might just be the angle. My spreader tips have a threaded J type fastener that is inside that spreader tip. You almost can't see it when it's in place. Maybe take that tip off and see if there is a hole where a threaded J type fitting might live.
The J hook on my spreader has to be adjusted with the tip off, kind of a pain to get positioned properly. I leave the J hook loose, get everything set correctly, mark where the J goes over the stay or shroud ( mine has both that run through it) then take off the tension, pull the spreader end, tighten it where it's marked then re-tune the rig. A bit of a pain, but it works...
If you don't have a J hook option, I agree with your assessment.
dj