Thanks everyone for the feed back, I had fun putting this together. There is no tank at all, I grabbed a piece of closed cell foam which is pretty rigid and tucked it in the top tubes. I then shaped it with a rasp and a razor. I did a pre-fit of the leather soaked with water and formed it to the faux tank and let it dry to form. After that it was tool time.
As for the pan, I had to drill holes in it and rivet a piece of 2 inch leather to the underside all the way around. I then had to punch holes and stitch. There is a 1/4 inch of leather outside of the pan.