Where is your CG? They say "CG (center of gravity):4 to 5 in. back from leading edge at the wing root."

Well for a very proficient flier with a strong power plant, and wanting 3D stuff, that can work. OTOH for a sport flier with a less than a barn-burning engine, it is a crash waiting to happen.

Your wing has a slight taper. Your mean aerodynamic chord (MAC) is "close" to the mid point of the wing panels in SPAN. Not exactly but that suffices close enough for toy airplanes with such a wing.

If you go to that point and measure back 25 to 30% of that chord, and balance at that point your airplane will not be tail heavy.

Now are your tail servos at the rear of the model? If so, take those servos, place them in the fuselage and use pushrods, stiff and braced ones. Then you are moving 3 oz. of weight forward to close to the CG. That is about a 3 to one advantage or the same as adding 9 oz. to the nose, except you remain 9 oz. lighter and get the same effect, CG wise.

Since I don't know the taper and using their figures for span and wing aera:

48.5" span with 747 sq. " aera = chord of 15.4" (for the perfect rectangle) however on a straight taper that should be close to the center of the panels span wise.

25% of 15.4 = 3.85 30% of 15.4 = 4.62

Any balance point between 3& 3/4" and 4& a half " will give you a nice flying airplane.

After you get proficient with the machine, then you can do some experiments and move the CG back in small increments, along with playing with aileron adjustments. Soon you will be having it stand on its tail, and all that stuff. Enjoy!