You can always try to pull out the cable and turn the nut more. Is the miata newer with a hydraulic cable system? That could be why it's easier. To get the safety sticker off, use that clear tape for packaging and use a razor blade to cut the rear off the bumper. I seen lots of Nissan and Toyota pickups in Oahu with the sticker already on the rollpan under the bumper, don't know if they passed withut the bumper though.