Want me to use a close up of what I used when I get home tonight? Not worried about them shearing OR backing out. My windows were held in with screws, I just replaced with sheet metal, and still used screws. I used the original screws when going through the aluminum trim pieces, and used bigger hex head screws elsewhere.
SN: I also had an area of rubrail above the door, where some of the rivets were sheared and or rusted/wallowed out. That area was damaged when I got it, and I had to beat things back and weld the crack. I used heavy duty hex head screws there as well, and they did start to back out. I screwed them back in tight and tack welded them. No more backing out