Radio reception question

There is truth to the ground plane theory. My personal opinion is that there is enough ground plane in the fender, inner fender and frame to get the job done and done well. That said, the ground plane theory (fact) is mostly for transmitters such as CB, Ham type of radios and has less, if no effect on receivers. There's a lot of other variables to narrow this down to the hood. I listen to AM in my truck while my wifes car doesn't pick up AM hardly at all. There's really no explanation for it. But, do you remember the Chevy antennas in the windshield? One half was the received and one half was the ground plane. Of course they stopped using them but I never had a problem with the one that I had. Maybe someone here will take off their hood and go for a spin so they can let you know how it works. It doesn't mean it will work for you though but I'd try it before you relocated your antenna.