I'm just finishing the construction of the SSE. Really nice plane to put together. I had the same concern, what I did was add blind nuts to the end rib at the location for the wing bolt. Easy to do and works great. Just drill out and add a 4-40 blind nut to the inside of the rib. I'll use rubber bands to hold it tight, but will zip tie it also for added measure-a small bag of a hundred cost nothing.

You will love the build.