Before you get too far along building things in permanent I recomend you do a trial CG balance test. Just dry fit, and tape on the tail feathers and place electronics, push rods etc. and motor with the prop, and everything close to where you think it should go. See where it balances. You don't have to worry about the little bits and covering yet, just the big stuff. Then if you need to move things around to get the CG right you will have a good idea what you need to do. The most important thing for a good flying plane is to have the CG right.