I have an indoor/outdoor thermometer to keep track of how hot the back of my Expedition gets. I drive pretty regularly with two dogs in the back, and over the summer and winter the temps can get a little extreme.
I need to be able to take it out to keep an eye on it remotely (it has about 1/4 mile range) but also have it not rolling around while I drive.
There was a coin holder there that I popped out, and used as a template for an insert to keep this mounted semi-permanently.
Printed with kinda crappy Amazon Basics PETG. If it holds up well, I’ll reprint it with better quality black PETG so it matches the car better.
Mine is sadly right in the window, but I might get tint at some point so that should help.
I see you have a window shade, but do you also have tint? On 100f days my interior gets well over 110 even with my shade up.