Thanks for the suggestions. I've tried option 6 in the past with mixed results, and my current solution of knotting through the mainsheet wears too quickly, so I'm now looking at a neater, long term solution.

Option 2 sounds good. I'm wondering how you attach the 3mm line to the core? Do you overlap them at all (that would create a thick bit of line, surely?) or do you some how stitch them end-to-end? What sort of line do you use for stitching?

Paul