The instruction manual is confusing about the 15mm distance but it is clear that you can balance it at 45-50mm with the wings off using the wing tube which is how I balanced my Ultra Lightning.If you want to use the Xicoy balancer maybe you could just use this method to get the proper C.G. and then install the wings and see where the balance point is with the wings installed. Then you would know for sure where the cg location is with the wings on and could use the your Xicoy balancer going forward. You may want want to make some changes after you fly the plane and then you could easily use the Xicoy balancer.