I see. If you had a picture of the tail assembly you could post, I'd be grateful. Even after cutting the vertical stabilizer to slide the elevator in, the slot only seems to be one foam board thickness. The elevator/horizontal stabilizer is doubled up. However, checking out some of the other build pictures earlier in this thread, it looks like both are only single foamboard thickness. Hopefully the picture below can show what I'm talking about.
Otherwise, it comes together quickly- this was just one rainy Sunday's worth of work. I wound up using some old wooden FT Spitfire spars in the wings and will probably use a cut down MS Corsair powerpod in the nose. Speaking of nose, that hatch is pretty sweet; I'm hoping there's room for a 2200 or 3000 4S battery in there.