A system comprises a first portable electronic device associated with an agricultural harvester and a second portable electronic device associated with a crop transport vehicle. At least one of the first portable electronic device and the second portable electronic device is configured to receive a geographic position of the other portable electronic device and, using only the first geographic position and the second geographic position, identify a harvesting operation performed by the agricultural harvester; determine a harvesting distance, a harvesting duration of time, or both of the harvesting operation; and estimate a current fill level of the crop transport vehicle based on the harvesting distance, the harvesting duration of time, or both.