If you want things to work as they should, picking a device that you can run Rockbox on officially might be a good step.
Sure, we push binaries for it, but the savvy user will notice that we don't provide a bootloader, or any means to install one, and that we quite clearly mark the port as "unusable".
From
the main page:
Unusable ports
Work has begun on porting Rockbox to these players, but much remains before they are usable:
...
Apple iPod Classic (6G)
...
I understand this is frustrating for you, and that its not what you're wanting to hear, but from our perspective you can't even boot Rockbox on this device in any official capacity.
[Saint]