Iagree. The C.Gfrom the plans or ARFmanual are what worked best (presumably) for the designer, or at least where he thought it should be placed initially. Your equipment installation is likely different. But it is a place to start and shound be placed there initially. The only way to judge best C.G.is in flight characteristics. No sense spending a lot of time static balancing a model - get close and get airborne. Unless your tank is at the C.G point it changes in flight, anyway. Even if the tank is there it changes from uplines and downlines as the fuel sloshes.

Us the time you save to laterally balance the model. It will make your loops more solid.