Would that very easy by using a step up and step down module controlled by a voltage regulator connected to the Pi3? It seems that everyone is racing to create something that every tech should know that most machines never work that they were intended to due the human error and customers misunderstanding. Since the pi is pretty much a low voltage object, it stands to say your cost would come down. This is just food for thought. I have hundreds of these boards as I into recycling boards.  

Try using the Beaglebone black or Cubieboard that are superior to Pi3. Boards are the mainstay of mining along with the heat rating. when you increase in wattage more heat. You will findout that if you enclose your board. Not to mention on your USB, I would recommend that you change you ports to 3.0 instead of the two for the future as the 2.0 will be phased out.