The Graduate is a nice looking plane.

I've got an older Bridi Sun-Fli 4-20 (similar to a small Kaos) that initially wound up nose heavy. Instead of adding weight to the tail, we cut an access into the bottom of the fuselage behind the trailing edge wing bolt mounting area and fabricated a small "box" out of balsa to house the battery in order for it to not conflict with the pushrods. Balanced fine after that mod, and didn't add any weight to the plane.
Just a thought, maybe you could test the balance with the battery in that location and think about the mod as an alternative solution.