Thank you for sharing your findings with us. I am sure that this will benefit a lot of users.
Through some testing of my own, I have had success in rotating the device 90 degrees in a counter-clockwise direction to take a landscape photo. This is exactly what the JPEG spinner is doing for you, however, if you do this with your device, you will not need to extract the KMZ and rotate the images and then recreate the KMZ. Images taken this way have displayed accurately in Google Earth every time I tested it on both iOS and Android devices so hopefully this works for you as well.
Avenza Systems Inc.