I have a 6 a.m. departure out of SMF and Avis shows no one is there until 6 a.m. . SMF has a number of departures around 6 a.m. so I don't know why they don't have someone there at 4 a.m. to accept returns. But in any event, I have never done an after-hours dropoff before. Am I taking a big risk that they are going find damage or charge me for gas (I'm filling it up at the airport) since I'm not there to protest?? Or, even worse, like Hertz, try to claim I never returned the car ?? What can I do to protect myself?