Security devices may include a side panel movably coupled to an attachment mechanism and to a top panel. The side panel may be positioned at least substantially transverse to the top panel with the at least one extension structure extending laterally outward from the top panel when in a secured position, and at least substantially parallel to the top panel with the at least one extension structure positioned laterally inward when in a storage position. Vehicles may include a trunk space with an attachment mechanism positioned within at least one slot in a floor of the trunk space. Other aspects, embodiments, and features are also included.