The stereo system in my trailer has a USB port on it and I just copy 32G worth of music files over, from my music library in the truck, to a
small thumb drive.
The music interface, in the radio, is pretty crude, but it will play whatever mp3 files you put on the thumb drive, in artist alphabetical order (there is a shuffle mode, but it only seems to shuffle inside the album folders).
I am not sure if the unit will recognize any thumb drive larger than 32G... it definitely choked on a 128G and I did not have a 64. 32G of MP3 files is quite a bit of music
-Brian