You can get the COG right on ..from a good COG calculator.... That leaves wing & horz. stab. at the wrong angles....A high cliff will prove that in a hurry. not joking. Remember the amount of tail trim lever needed to do a short level flight. Reenter that into the plane on landing. Does it look minor ?
Adjust wing / tail till acceptable........Here is were the time gets boring. The final adjusting of surfaces level and moving COG weight to get a ALMOST flat glide. A small amount of below level angle is OK. A few degrees. Lots of short flights needed by me.

Now coach ?.......OK You can play with motor angles. I do this with all planes. Some were designed perfectly. Others by Brick Layers.

Rich