Robert that is impressive work, thanks for the pics of the tipping wheel process!
As you said, Im learning to weld so I've been focusing on the mig process of tacking, planishing, grinding that you have outlined. I didnt take pics of every stage but I did take these just before the last series were done. Its not there yet on the seamless look.
Then after a few more series its about as close as I have been able to get it. Shining a light from behind I dont see any pinholes although there are some welds that shrunk circumferentially and arent flush causing the shadowed edges. I didnt want to sand it down too much cause I have been concerned about making that area too thin by grinding out too much metal. The last pic on the right is the inside of the panel.
So far the seam is flush with the straight edge as I go up and down that area of the panel, and also the template I took off the cab is still in line too.
As for the next step I am trying to get the panel sized to be welded in. Since the planishing would be difficult with that bracket in the way, Ive decided to cut out a bit further and use more of the panel.
Let me know if the welds are decent, if Im doing something wrong please let me know.