Nice to read lots of reply since the last time I post here. As per OP, you changed two physical characteristics of the plane. Your concern of being tail heavy is correct for static characteristics depending on the amount of expansion. You will find it easy after you check the weight, existing CG location and the dynamic requirements based on the increase of its chord and control surfaces. Expansion might also affect other loading such as servo, etc. but it might not be a big issue since it’s your own design aircraft... Good luck on your maiden!