I live in HOT Dallas, TX. my car is in the sun while at work (40hr week). I also bought the sunroof sunscreen from Smartmadness. No problems with the glass yet.
You are right, It is too snug, and hard to slide into place between the glass and ultra thin paper/fabric pull screen thingy. I think that is my fault, I got the first one b/c they asked me to measure the sunroof when I ordered.
Hey, it isn't the easiest thing to measure, standing sort of on your head with NO one to "hold that end of the measuring tape will ya".
Next one to order, please tell them to cut an inch off the length and 1/2 off the width of there pattern. I trimmed mine with scissors and it is better now. I put it in that slot WHITE side up towards the glass and silver side down. A guy in my Dallas Smart car club told me he does that to have it work like that "radiant barrier" stuff they put in your attic to keep the house cooler. Silver side toward the house side not the roof side.
I think this helps keep the car cooler and puts less heat on the glass itself.
Vicki from Dallas
P.S. it is easier to slide into place from back towards the front, with the pull screen closed, there is a slot you can see when standing at the open hatchback.