When we had to replace a broken mainsail
batten a few year ago, the vendor had to grind a taper into the one that he had in stock. To avoid glass fibers getting everywhere afterward, he simply ran a length of clear packaging tape along each side of the batten and trimmed the excess off with a sharp knife. It not only prevented the dread itchies, it was slippery and made inserting the batten easier... and to my surprise, was still intact several years later when I removed the batten prior to replacing the sail.
I see no reason this method would not work for your application... easy, quick and cheap
-- how's that for a recommendation?