I recently had to deal with a similar situation. I have a CUCV I got from the military that had holes on both quarters. Now welding it up using the washer method works greats and is fairly straight forward. The one problem I had to keep in mind up here in Upstate New York was RUST. And when ever you weld you have some kind of corrosion even when you use weld through primer. I work in the collision industry and we use alot of panel bonding adhesives to replace panels with. By using panel bonding adhesive you take away any heat issues and there is not corrosion to deal with. What I deceided to do was tap down the holes a little first and grind around the outside area of it about 1/4 inch. Then I cut out small metal patches from sheet metal slighty larger than the holes. The I used a panel bonding adhesive by "Fusor" (doesn't have to be same brand), and I put a good amount on the patch and put it over each hole and held it in place with a clamp. They dry pretty quick but I let mine sit over night. Next day I sanded down the patch with some 80 grit sand paper so as to give the body filler something to stick better to. (I used Allmetal but any good filler will work). The just basicly apply body filler, sand, prep, and paint. I would suggest coating the back side of the hole w/ a rust preventive spray like Rust Free. Hope this helps.
