Well, the crossmember survived the hammer whack test pretty easily and I wasn't gentle. Whacking it did loosen some of the remaining scale, which was good. The bad is that some of the scale that came off included parts of the rivet. I'm including 2 pics. The first shows a close up of the thinnest area. The second shows the rivet in that area. It's so hard to actually see the rivet that I used a screwdriver to point it out.... To me, the rivet looks compromised, but I'm a lay person. What do you all think about the rivet? Also, should I try to use something like POR to stabilize the rust or should I just leave it alone?