if the trailer 20 has i beams 142 that are not perfectly aligned and depending of the installation configuration of the skirt panel 38 along the trailer 20 the front portion 58 of the skirt panel 38 can proximally lean toward the center of the trailer 20 hence progressively curving or bending and be located at an angle with the i beam 142 of the trailer 20 as illustrated in fig2 and fig2 the size of the openings 130 is designed to accommodate a flexible installation of the pair of clamps 134 that can be located to accommodate position variation with for instance an angle u03b2 thereof as mentioned above the strut portion 84 is preferably located on the trailer 20 to have the exterior of the skirt panel 38 vertically aligned flush with the side wall of the trailer 20 the skirt panel 38 is hence used as a vertical continuity of the trailer 39 s 20 side wall the alignment of the strut portion 84 might be challenging to achieve alignment guides 250 are provided on the trailer contacting portion 114 to assist the positioning and the installation of the strut portion 84 on the trailer 20 the trailer contacting portion 114 incorporates alignment guides 250 embodied as protruding members located at predetermined locations on the trailer contacting portion 114 from the skirt panel contacting portion 118 used as reference plane for laterally locating the skirt panel 38 the alignment guides 250 can be seen throughout the figures using some different configurations of distance and shape the alignment guides 250 can alternatively be embodies as extrusions.