I made one to be affixed to the outside of the frame with velcro (after propping the window open, or removing it) for our first trip to Mexico. It never got hot enough to need it but we still carry it when we are planning a long stay where we might need it.
If you want others to be happy, practice compassion.
If you want to be happy, practice compassion - The Dalai Lama
1984 310 Limited Motorhome
Courtesy Parking (W/S/E/Wi-Fi) on I-5 in Northern California, 70 miles from Oregon border