Didn't get to do much tonight, but I did get the trim tab gap filler reinforced from the top. I used two layers of 1.5 ounce fabric for the reinforcement, as there's not much room, and there's no real need for a large amount of reinforcement. The gap filler is totallly non-structural. I'll give it some serious tugging tomorrow afture cure, but I'm confident it will be plenty strong.