Sterling is a FHU State park, one of only a few. There is Haas right on I-96 and then Wayne County RV Park and Fairgrounds right off I-94. These might be the closest.
If you are looking for quiet with electric only then Proud Lake SP, Pinckney Recreation Area, and Brighton Recreation Area would be the next best. All are within 40 minutes of downtown Detroit. It may depend on where you are going in the city. There are also some county parks in the northern suburbs or, with passports, there are several campgrounds in Canada. Just a short drive over the bridge or through the tunnel.