There will certainly be a plethora of opinions on this subject. For back glasses I have two opinions... LED's to reduce heat and Krylon Triple Thick for preservation. I have had my best luck coating with Triple Thick at lower ambient temperatures as the Triple Thick likes to crystalize quickly if it is warm out. To minimize the crystallization (note...I also spray right over the score windows), I use two cans of Triple Thick at once. Using two cans enables me to get a single very wet coat down in just one shot.