Vertical CG would have nothing to do with what angle the fuse is in level flight. In fact, lengthwise CG has very little to do with that. The only thing that will control the angle the fuse flies at will be the angle of incidence the wing is mounted on the fuse. But Vertical CG has a lot to do with what the model will do in a vertical upline. Most models that have been originally designed for IC engines need the batteries in the belly in order to have the vertical CG in the designed location. Think about the IC engine cylinder sticking down, then the exhaust system on the bottom. If the packs are located too high, the model will pull to the canopy in an upline, requiring more downthrust.