You can install a full Tonneau with the windshield in place: I remove the seats for better access. Measure on the new Tonneau cover the distance you want the two snaps L & R of the zipper. Plot that measurement off of the center rod location on the dash. From the underside of the dash, drill the two snap stud holes a bit smaller than the snap stud. Use a mini Phillips head ratchet screwdriver to seat the snap studs. (Wait until later to do the snaps forward of the door) To match the studs to the rear section of the tonneau from center, I press down on the material and mark with chalk one location at a time on the new tonneau cover alternating left to right. Then do the snaps forward of the door and lastly the two at the windshield post ....Constantly check.... for any variation as you install each stud and snap . You can, do this yourself. (Me, I take the 15 minutes to pull the windshield as it's so much easier)