A tie-down assembly for selective attachment to a structure at an oblong aperture defined thereby and detachment therefrom includes an anchor arranged along an axis. The anchor has an oblong-shaped section configured to be inserted into the structure's oblong aperture. The anchor also has a knob section which turns the anchor's oblong-shaped section about the axis when a torque is applied to the knob section. The assembly also includes a rail mount configured to abut the oblong-shaped section, and defining a pocket for accepting the knob section and limiting rotation of the oblong-shaped section via contact with the knob section. The anchor's oblong-shaped section and the rail mount are together configured to sandwich therebetween material of the structure proximate the oblong aperture after the anchor's oblong-shaped section is inserted into and turned relative to the oblong aperture to thereby attach the tie-down assembly to the structure.