What I do to test if it is stable I take that stratocaster clone I have and I place the plan over it and see how much it differs on one side and I try to make it have about the same amount of wood extenting. Of course if you think that the cavities will be diferent...there is alot of difference in moments in a different shape, the neckthrou design will combine wood of different densities makes the stability issue realy hard to figure out.