Okay, so here is what I ended up doing, and it was so simple that I can’t believe I didn’t just try this to begin with. With a huge library I would think it’s not very practical, but here goes.
I went into the device’s Music folder in the “Auto Detect” mode under USB settings, so that my music files would show up.
I used the CTRL button to select all the songs I wanted in the play list. Right click >> create play list. Then I just renamed it. It shows up in the device’s menus and everything as a .PLA file.
Thank you to everyone who tried to help me with this. I may keep working on the problem with music files not showing up, because if I added ALL of my music to the device it would be a huge pain to do it the way I did it just now.
<3