@SomeJoe7777, thank you for your excellent work! I'm a kind of experienced Windows user, but I almost forgot about disk partitions.
I have an issue and would like to hear your thoughts. My USB stick is Samsung 256GB, and I want 128GB for TeslaCam for more capacity for Sentry and the rest for my music. I followed your instructions and formatted both partitions as FAT32 with the Ridgecrop utility.
I also created the TeslaCam folder in the first partition.
Now, my dashcam icon has an X. Music works fine. My car is a 2017 Model X with upgraded MCU2 and AP3, firmware 2021.4.16. From the menu in the car, I tried formatting the dashcam disk - after that, TeslaCam started working. When I insert the USB stick into my PC, the TeslaCam folder was created on the second drive, and all the music files are gone.
So, I'm guessing that there might be a possibly stupid logic to determine which partition to use for the TeslaCam, in the car firmware. In my case, the size of the TeslaCam partition is larger than the music - do you think that would matter at all?