THIS WENT ON LATE. WE ULTIMATELY REALIZED THERE IS NO SHORTCUT. IF YOU'RE STARTING HERE, DON'T BOTHER GOING BACK TO THE START TO READ THE THREAD. THE SOLUTION LOOKED PROMISING, BUT IT WAS JUST A SIREN LURING US TO FAILURE. WE ENDED UP PM'ING, BUT THAT LEFT ALL OF THIS MESS.
looks like getting around fileprovider is a dead end. but i still believe it's possible to construct the special uri that fileprovider uses by hand, ie, without support-v4. i would imagine that's where all the kb's are. it's just a method that prepends content:// instead of file://. not ready to submit just yet.