Today, I split the wingtip along the center outboard edge. That didn't relieve my problem, which was the upper edge between the top and outboard side. So, I made a perpendicular cut in front of the false spar and it relaxed. I then sanded 1-2" back from each edge, and tapered the edge. I cut a small 1 inch wide piece of fiberglass and glassed it in place with polyester resin. I'll let that dry, then sand back some more and add more layers.
