With the tube now gone, I set about fixing the 5/8" hole in the forward end of the VS top rib.

I cut a piece of windows screen to fit the hole, and bonded it in place with JB Weld. Once it sets up, I'll apply a layer of gray silicone caulk over the area and smooth it with my finger. Then I'll put the cap back in place once the painting is finished. You'll never know it's there, it will be nice and durable, and will keep moisture out of the vertical stabilizer.