I think I would make sure the dowel was in there. If something were to happen during flight, and VF knew that you had left the dowel out intentionally, they may be less likely to help even if something were to fail that could be attributed to the way it was built at the Factory. That way if a joiner were to fail, or a wing would warp bad, you could at least say that you built it the way that the instructions said to. Then anything you can do on top of what the manufacturer suggest to add strength to the Plane without adding to much additional weight would probally be looked at as a good thing by the Manufacturer. Also I doubt that I would trust the Trailing edge of my wing to two nylon bolts alone. Gary's mod basically helps to create a snug fit between the fuse and the wings, and to also help to insure that the Trailing edge cannot come off the dowel. Just my .02 anyway for what it is worth!