Alternative Fuel Tank Suggestions

[Humble]

I think the difference to the polar moment of inertia would be almost nil given the amount of mass and it location. Most of the weight is between the front wheels and there's only 70lbs or so at most. Given that you're dropping that weight 18" or more makes a difference in the amount of body roll you get. I think it would make a big difference for turning corners since that mass gives the front end more bite. For sprints you can dial in your front axle weight with a little more or a little less gas. In endurance races it's a compromise because your handling will change as you drain the tank but that's true for any lighter car.