sounds like good way to do it. but like you say won't help my immediate problem. I;m sure those little star washer retainers after 5o years get pretty thin!!
I think I will get couple 1/2 in lock washers and stick the mig head in there and tack weld.
I just did mine and went in from the door and got them started and then used a small pry bar and a box wrench that fit on them to pry them on. Did the same on the trunk ones too.