Sensor systems, methods and machine readable medium are provided for a cargo vehicle. A plurality of sensors are arranged about an opening associated with a door through which packages are unloaded from a vehicle or trailer. The plurality of sensors are configured to measure an unpacked depth of the vehicle or trailer. A processor is provided in communication with each of the plurality of sensors. The processor is configured to receive measured data generated by the plurality of sensors, determine an empty volume over time of the vehicle or trailer based on the measured data as packages are being unpacked from the vehicle or trailer, and generate instructions regarding loading packages in a subsequent vehicle or trailer based on the determined empty volume over time of the vehicle or trailer.