A tonneau cover access panel assembly connectable to a vehicle that eliminates the need for side rails to both locate and tension a tonneau cover. The assembly also reduces weight and complexity. The assembly incorporates a readily accessible rear latching system that reduces or eliminates interference with the tonneau cover during operation. The assembly also incorporates a tonneau cover tensioning system. The tension seals out environmental elements and holds the tonneau cover and locating bows in place. The assembly holds the tonneau in the closed tension state keeping the tonneau cover secured and tight until the cover is opened by an operator. The assembly is movable between a closed position and a fully open/stowable position and any intermediate positions. The assembly is also movable between at least a first open position and the deployed position for more limiting access to the cargo bed of the vehicle when desired.