Hi Jeffrey,
When I made a similar sized sail for my previous boat I used 3mm Dynema 12 strand at luffs
and leaches. As dyneema is famously difficult to knot securely I used Mobius Brummel
spliced loops at the battens. I had to make a few practice loops in order to allow both for the
splice shrinkage and slight elongation when loaded.
Although time consuming I felt it worth the effort.