One step backward - two steps forward. I cut a new panel for the top and bottom of the left aux tank. I've been using the throatless shear to cut the .050 material and that works very well. This tool came in handy for this.
After bending the panel in the brake I wanted to cut the hole for the filler neck and move on. This time I cut several practice holes and made adjustments until it was right on. I cut the actual hole with a little more apprehension this time. After deburring I test fit the filler neck and it was just a little tight so I carefully took off a little more. The neck fit nice and snug in the hole. I cut the hole in the other aux tank and it came out well too.