I finally got this door hinged and this will be the port for charging R2.
As you can see in the pic, I have a small magnet that will keep the door closed. I will not be adding a servo to this door because it will only get used for charging. I have a 24v. battery charger that has a aluminum connector for charging. The connector will get dressed up to look like the connector in the movie. It won't be exact, But it will be close. I also plan to build the charge pack and hide a actual battery charger inside. The only problem will be that the movie shows very little of this charger and I'll have to guess at some of the details.