A cover device includes a cover plate having a body portion with inner and outer surfaces. A deployable retainer mechanism is positioned on the inner surface of the cover plate and includes a plurality of engagement features operable between retracted and deployed positions. An adjustment mechanism interconnects the deployable retainer mechanism and the cover plate, wherein the adjustment mechanism includes a portion thereof that is accessible from the outer surface of the cover plate for moving the plurality of engagement features between the retracted and deployed positions.