An integrated spray-treating system within the bed of a dump truck to allow for complete internal coverage of such a bed as well as that of a movable cover present thereon is provided. Such a system includes at least rotatable spray nozzle device that permits spray coverage of the entirety of the bed as well as the cover. Additionally, the system comprises a pressure component incorporated with a standard hydraulic component of such a truck as well as a suitable controller configured for the driver to operate the system from within the chassis. The system may be provided as an add-on to an already-existing truck or included within a typical truck manufacturing process. The overall operation thus permits the driver/operator the capability of coating the bed surface to prevent undesirable asphalt or other material build-up, caking, and the like, therein.