Since the ballast is lead shot encapsulated in resin, the ballast will not work, since it is no longer a single piece of metal that will serve as a counterpoise. The copper strips inside or outside of the hull, or a Dynaplate on the exterior of the hull will work. Another idea is to use copper strips on the underside of the cockpit floor. You will have to disconnect the conductor if you want to open up the floor though.
I do not recommend attaching any electrical connection to aluminum fuel or water tanks, as it will surely induce electrolysis corrosion, and soon you will have a leaking tank.