You are not supposed to be able to rotate the Fuel Truck, or any other vehicle, while its performing a service.
The only time you can rotate a vehicle in the GSX, is when you customize its starting position on the parking, but the Fuel Truck starting position cannot be customized (and it won't change your issue if it could), since it's not a service that starts on the parking.
If your issue is that, with the new fuel position, you cannot see the fuel counter, the only way to solve this, is for use to move the fuel counter on the other side of the model, which we might do in a future update.