A hitch receiver with four walls forming a tube that includes an integrated clamping device for immobilizing inserted accessories. A flexible tube wall acts as a pressure plate to press against the accessory as force is applied. The clamping device further utilizes a backstop attached to a rigid portion of the tube and accommodating a mechanism for generating force. Force can be generated mechanically via a threaded rod operatively connected to a threaded opening in a block located in the space between the backstop and the pressure plate. Clamping force is applied to the pressure plate by the tip of the threaded rod as it is turned in such a way as to force the threaded block against the backstop. Force is applied until the pressure plate deforms, contacts the adjacent wall of the inserted accessory, and presses the accessory against the opposite tube wall.