That is get some Stainless Steel Nylon coated fishing leader wire, with correct size Crimpers. I would use thinest wire (which is also cheapest) as it's only going to hold your Gate Lock Pin, not a grouper. Then make a Loop with wire at one end looping it through Pin ( buy a pin with a ring on it) and Crimp loop in place. This loop should be small so looks good. Say 15 mm or less.
Then loop wire around mast leaving enough length to be able to work with pin easily, make the second loop in wire around the mast, pull loop fairly snug to mast, crimp wire to make a fixed loop around mast and cut off excess wire at crimp.
