Great feedback guys . . .

Of course, when you say MIG welding, I am assuming that you mean with the use of gas. The flux core wire sucks.
Yep - got gas now. I actually DID weld the trunk pan successfully with .30 flux core. But it was NOT easy. I had to try it - and quickly realized it was not going to do an acceptable job on outer panels.

... typically leave a gap between the two base metals the diameter of the filler rod. You can't do that with MIG because it will blow away. You will have holes everywhere.
Actually on the first quarter, I had a gap equal to the cutoff wheel or slightly larger. I had to weld it colder than I liked to prevent blowout.

I gonna try to tighten that gap up on the second.