Well,there is one last option you can try,, Instead of drilling holes and hoping your going in a strait line,which you will probably end up hitting other parts of your plane. Then you will wonder ,Was It Worth screwing up a perfectly good plane, Maybe you can incorporate the servo wires into the outside shell of your plane. Use your imagination and enclose them in something and maybe cover them in a different colour.,Who Says That you can't do this, If you do,it will be special to you and unique!