I have driven many miles since this topic and I have had zero problems with leakage ever since. I got two gas caps by damraider; one on the Barracuda which looks absolutely killer in the aluminum look on the silver body, and the other on the Valiant. I kept that one stock (aluminum) for now as well.
A photo of the gas cap today, after a test run I did and cleaning the new tires - hence this picture.