A open frame generator is a hum on the wind at around a half mile so I figure that's a good distance. Does that mean it's ok to camp closer if you have a quieter inverter generator? Only if you want to hear my open frame. :)
Actually we very rarely run the generator while camping and if no one is near, our dogs have nothing to bark at. We work hard to isolate ourselves and even in spots that will take multiple rigs I will park the truck to block the entrance of the clearing.