If you return after hours, the car isn’t technically returned until the office opens and the agent gets to returning your vehicle. Therefore, you would be charged 2 days. You mention you are using points, they wouldn’t charge the second day on points, they would charge the cash rate.

Platinum may may have some benefit that provide does a return at drop off time, but I doubt it as there is no way to k ow when the car was actually dropped off.

If you do a drop off, I’d suggest taking photos of the mileage, fuel, and all angles of the vehicle for your own safety. I like to take a photo of my fuel receipt next to the odometer and fuel gauge, so there are no questions if an issue arises. I also make sure to get the returning location in one of the exterior photos. I’ve never had a problem, but better safe than sorry.