What about sitting your own baseband station atop the vehicle's cell device? Is there a power at which you can broadcast such that nothing outside the car can

What about sitting your own baseband station atop the vehicle's cell device? Is there a power at which you can broadcast such that nothing outside the car can detect it but the vehicle's cell device still registers it as the closest "tower" and therefore connects to it? Then you could build your own little in-vehicle pihole and man-in-the-middle your way to an ad-free commute.