To all of you doing all of this roof preventative work in the hot sun West, have you though of getting an application of a RV rubber roof paint-on sealant/coating? I am considering this, and the specialized tech I called said that it made the roof so much cooler that you could walk on it barefoot in the sun. Heat gain through the roof where I live is a major concern. I believe that these paint-on coatings need no further caulking or UV protection maintenance. I was up on the roof on an 80 degree day last week working with the air conditioner, and was amazed that the white rubber roof was hot enough to keep me from putting my bare hands on it while crawling around (fortunately I had a rag with me that I could use to insulate).