Make capacitor backpacks fit into Baubles back slot when the mod is installed! When I'm playing the game, I really don't want to replace my chestplate, something that is providing me with almost half of my armor, with a capacitor backpack!

Second to that idea, make it abominable with armor, so I can wear my armor and capacitor backpack at the same time!

You can attach it with to chestpiece, says so in the manual .-.
Just craft the two together.

That said, I can look into baubles compat (last time I worked with Baubles, it had 4 slots, and I wrote TG to add more. Didn'T even know Az added more to it). Should be pretty easy if the API hasn't changed.
Although I bet he still hasn't moved to Capabilities.