Subject to applicable limitations of law, Service officers and Customs officers may detain for inspection and inspect any package, crate, or other container, including its contents, and all accompanying documents, upon importation or exportation. The Director may charge reasonable fees, including salary, overtime, transportation and per diem of Service officers, for wildlife import or export inspections specially requested by the importer or exporter at times other than regular work hours or locations other than usual for such inspections at the port.