Also, progress in small steps, but I put two more sides on the tank today. These small pieces were cut at an angle to match match the base angles on the rear plate, and bent approximately 30 degrees to mate up with the sides of the stock tank base.
For now, I'm just spot welding all the pieces together for fitment, once its a full build I'll run a full weld around all the seams.
And here it is with three of the God-knows-how-many small plates that will ultimately build up the entire tank.