Yup, it takes a lot of panel. And ok, you would also have to drive around, or put a brick on the pedal. But the point I was trying to make, is you need to carry a big ass battery in the car to be able to charge from the car battery and still be able to start the car and drive off, not to mention the wear on the car battery doing a 100% discharge. Some folks just don't do the calculations and think they can charge with tiny solar panels, or a small cars starter battery.
The most practical way to carry charging is likely to be just to buy a small generator, but then you get to listen to the damn thing. A big deep cycle marine battery might do the trick, and then charge it back up when you get to the b&b or hotel if you want silence at the campsite.