A generator you would need to power the vehicle in transit would need to be monstrous. The generator you've listed would charge the car at a ballpark rate of 10 hours. As an illustration, going 60mph for one hour would consume about 18000 watts, while the generator (running that same hour) could produce 1596 watts, about 5 additional miles. Also, most generators output AC voltage, and the battery pack (I can promise you) is DC voltage. You would need an additional rectifier to resolve this.
At this point you'd be better off adding an additional 5 to 10 battery cells to get more miles, rather than buying an enormous generator, then a rectifier, and still be buying gasoline.
Electric conversions are great for around-the-town use. But they're not intended to be the "everything" car. If you're going out to the country, use a different car.