Sounds like a good plan. Mine weights 5.5lbs (heavy). I'm using a 6v cad 600ma pack. I used it to adjust cg by sliding it further and further back over the wing untill it was at the trailing edge of the wing. I have the reciever just in front of it. It still took 1 oz of lead in the tail to get 4 3/4. Your efforts to keep this light will be rewarded.
I question the need for a 10oz tank though. IMHO that's enough to fly all one day and part of the next and it's all forward of the wing.