Advice...15 size fast plane....
If you buy a Sig wonder, I will tell you how to make it a bullet.
Build the wing but dont join it. Get the motor mountand measure the width. Place the wings together and mark off the mount and you are going to put the engine in the wing, and your not using the fuse at all. Make a bay on the back for the elevon servo. put the tank behind the engine and the throttle servo behind that. Make the bays deep enough to just leave out the control arm and secure. you can figure out the rest. 90+ mph with that rossi 45, make sure you ballance and center the thrust line.