I have no idea what I'm doing. But I'm doing it anyway. So far so good.

Hehe! That's what I tell myself everytime I pick up a wrench or do anything electrical related. About that fender channel, some of the spot welds were broken on both mine & I was able to work loose or rotary tool w/ thin disk the others in order to get back in there & clean/ repaint. I'd go with drilling more holesaw holes - see what I did on my underbody channel, same idea as you have..... Loooooking goooood.....

I wanna see you fix that parts tailgate you got from me... just for fun... ;p