A detachable tonneau cover panel assembly for a vehicle tonneau cover includes a panel portion structured to be detachably connectible to a panel of a tonneau cover, and at least one mounting bracket attached to an interior side of the panel portion and structured to enable mounting of an object thereon. An optional shield may be attached to the panel portion to enclose and protect object(s) mounted on the mounting bracket(s). The tonneau cover panel assembly is structured to be easily detachable from other panels of the tonneau cover and man-portable so that a user may use the tonneau cover panel assembly as a carrying case for any objects mounted on the mounting brackets attached to the panel portion.