I was very pleased with the fit on the quarters, i think the detail along the back glass was the only problem.
Both sides of the small flat area are very rigid, I didn't feel I needed to support the back side with a dolly and once the panel is welded in it is difficult to get to the area behind. The dolly would also have to be shaped to accept the cove, plus the cove is wider the closer you get to the quarter extension.
I sanded the ends of the dowel round also to prevent any sharp edges from denting the quarter in a line or crease perpendicular to the cove.
It was actually very easy to form the cove which is very slight, you don't have to hit very hard.