The body is fiberglass, IIRC. You should probably put shielding around the electronics (pick-ups, pots, etc.) if you haven't already. Hmm... I don't know if you'd want to put copper foil all over the inside of the body or paint it with Conductive Shielding Paint (I don't know if it'd affect the acoustic sound of it or if the paint'd melt the fiberglass' resin ). Maybe build a thin box just under the maple cap that'd surround all the electronics and shield that? All that might be overkill, huh? Those hollow bodied jazz guitars don't have that much shielding, do they?
Ooh, and yeah... add some piezos like Litchfield said!