A perimeter frame for a sunshade module includes a sunshade opening, a guiderail, and a housing. The guiderail includes an end face, and a guideway, a mounting flange, and an attachment channel extending therefrom. The guideway opens inwardly to the sunshade opening, the mounting flange projects outwardly away from the sunshade opening, and the attachment channel opens downwardly from therebetween. The housing includes a guiderail adaptor. The guiderail adaptor is inserted into the attachment channel, secured to the attachment channel using a fastener installed from above the attachment channel, and engages the attachment channel from below.