Here's a post I did ~6 years ago, https://www.irv2.com/forums/f115/don...ng-246255.html
all of the windows have stayed fog free.
I did 3 of my windows. I bought the material from DK Hardware, cost ~$100. The drivers side window I did was the hardest because of the shear size, I did this myself working off step ladder on the outside.
The spacer material I bought has the desiccant to draw moisture out of the air that is left inside and would eventually cause the fogging, not much money to try and do this right.