Nissan Sun Shades & Snow Covers

Ordered, received and been using the window shades. Did not have trouble with installation, except through my own error initially. Living in the desert has it's pros and cons. Major con for me is the damage the sun can do to a vehicle, as I learned my first summer in this climate. Although my vehicle is older, it has only 51K and is in excellent condition, mechanically and physically. It also holds a dear place in my heart, as I received it from my father's estate. We spent many hours together in the car. The interior is black leather and I intend to keep it in top condition. Hence, the reason I was willing to spend extra for the WeatherTech product of shades for all the windows. Coming from Illinois, I've heard their commercials..forever. I am pleased, overall, with the product, but am frustrated over the back window shade's performance. It will not stay in place. Was able to solve same issue with windshield, but simply using the visor extensions and allowing them to be additional support. But, I cannot figure out what to do with the back window. Adding anything would be futile, as command strips or similar product would not hold up to the heat and sun. Definite difference in the car interior's heat, but I want to keep the sun out when the car is not in use (most of the time), while parked in the sun (with no option). Would love suggestions on how to solve my problem. more details on - https://www.carid.com/weathertech/windshield-sun-shade.html#reviews