An enclosure device for forming a secured enclosure area within a cargo area of a vehicle is disclosed. The enclosure device includes a front panel and a generally planar deck panel that extends from the front panel. The deck panel includes a pair of pair of spaced apart left and right sides that are adapted for extending over the wheel wells and the sidewalls. The deck panel also includes an aft edge that is adapted for extending to a location directly below an upper lip of the aft end of the cargo area when the front panel is adapted for fastening to the vehicle. At least one of the spaced apart left and right sides includes an abutment edge that is adapted for being positioned next to the sport cage upright, so that the secured enclosure area is created below the deck panel.