I had initially thought of centering the contoller in the fuel tank area, but that would require an addtional cross member to support it. By using the existing cross member, a thick walled piece of rectangular tubing, the contoller is located toward the back of the fuel tank. That will free up the front of the tank for other electrical components and cables.
A little frame modification was required to have access to the inside of the rectangular section. There was already an opening on one side, I just needed to duplicate the opening on the left to allow room for a wrench and to get the bolt placed. The section of the tubing is almost 3/8" thick so I'm not too worried about affecting structural integrity when removing another piece.