I would stick with steel or stainless steel. I would not trust aluminum. First if you back into something parking or in a crash it will tear easily, second I saw first hand the remains of a Ferrari 458 that burned as a result of a engine compartment fire. There was NOTHING left of the aluminum and magnesium parts, from upper control arms, frame rails, to the intake all the way up to the windshield BUT the steel fuel tanks were intact. That made up my mind no aluminum fuel tank on my 56 Dodge.
Scott