I believe someone posted before (Steve A?) what the reasoning was for putting the battery (weight) on the Starboard side and it had to do with torque steer or thrust from the motor. It helps offset it. Something like that. There is a legit reason for it being that way, however, that said, if you have a portable tank, I'm guessing that 6 gallons of fuel is heavier then a battery, so its offset anyway.