Bill, I know nothing about the bakpac. If it is a hang on, then do you need to modify the hood to the nano? My jbl 24 nano is stock with pc lighting and tight fitting hood.
I did find one from oceanic for nano's that looks like it might sit compeletly inside the back of the nano. As you can tell, I just started looking at getting this thing, and still not sure if it is the right move.