Ayuh,.... To reduce the length needed, 'n to lessen the wirin' rats nest at the batteries,.....
The tank, technically, it should have 2,.....
The "Bonding" system uses like a 10/ 12 ga. wire(usually green) to electrically connect the tank, the fill fittin', 'n other fuel metal hardware to the motors block, 'n anodes,....
The fuel gauge sender should also be grounded to the motor's block, with a 14/ 16ga. wire(usually black, or now a days yellow), for gauge purposes,...
The battery's (-) terminal, is of course also grounded to the motor's block, tyin' the entire hull's electrical system into a Circuit,...
Or actually, Many circuits,....