Depending on engine weight, move them back. If you are using a very light two stroke, leave it alone, otherwise move at least one. For my Saito 72, I moved both.

I started by picking the spot to give huge throw to the elevators. I put that one just below the stab. Put the rudder servo just below it. I cut the squareish hole completely through the fuselage where the servos go. I cut two pieces of 1/64 ply the size and shape of the fuselage around the servo area. I cut the same squareish hole in one piece of ply. The un-holed piece goes on the back side. I epoxied the ply pieces down and added 1/4 hardwood rails on top of the holes for servo rails. This allowed me to install HS-225MG servos without sticking out the back. I ran the wires along the side using the plastic clips included as pushrod mounting clips.

For my plane, that put the CG almost centered on the spot noted on the plans. Believe it or not, it was still a touch nose heavy.