A clamping device for use on a crossbar of a vehicle rack, the device comprising: a body including a docking surface having a docking interface for connecting the body to a cargo-specific rack accessory, and a mounting surface configured to contact an outer surface of a crossbar, the mounting surface being spaced from and opposite the docking surface; a clamping assembly operatively connected to the body, the clamping assembly including: an actuator and a cleat operatively connected to the actuator, the cleat having an elongate stem passing through and depending from the mounting surface, and a first arm and a second arm, each arm extending generally orthogonally from opposite sides of the stem and forming the general shape of an inverted "T"; wherein the stem has a longitudinal axis, and the clamping assembly is configured such that moving the actuator between a first position and a second position causes the cleat simultaneously to rotate on the stem axis and to translate along the stem axis, the clamping assembly further including a cam surface operatively connected to the body, and a cam follower configured to interface with the cam surface, the cam follower pivotally coupled to the stem of the cleat, the cam follower being axially coupled to the stem of the cleat by a biasing assembly; wherein the cam follower is rotatable about a cam follower axis, and the cam follower axis is aligned with the stem axis; wherein the clamping device further includes a biasing member configured to axially bias the cleat downward, wherein downward is defined as a direction from the docking surface orthogonally toward the mounting surface. a body including a docking surface having a docking interface for connecting the body to a cargo-specific rack accessory, and a mounting surface configured to contact an outer surface of a crossbar, the mounting surface being spaced from and opposite the docking surface; a clamping assembly operatively connected to the body, the clamping assembly including: an actuator and a cleat operatively connected to the actuator, the cleat having an elongate stem passing through and depending from the mounting surface, and a first arm and a second arm, each arm extending generally orthogonally from opposite sides of the stem and forming the general shape of an inverted "T"; wherein the stem has a longitudinal axis, and the clamping assembly is configured such that moving the actuator between a first position and a second position causes the cleat simultaneously to rotate on the stem axis and to translate along the stem axis, the clamping assembly further including a cam surface operatively connected to the body, and a cam follower configured to interface with the cam surface, the cam follower pivotally coupled to the stem of the cleat, the cam follower being axially coupled to the stem of the cleat by a biasing assembly; wherein the cam follower is rotatable about a cam follower axis, and the cam follower axis is aligned with the stem axis; wherein the clamping device further includes a biasing member configured to axially bias the cleat downward, wherein downward is defined as a direction from the docking surface orthogonally toward the mounting surface.