[Cobalt289]

Thanks all! Yes, I was hesitant about drilling a hole and just running a screw into the sidepipe with the hope of it actually working, but since I knew the alternative would take a lot more time and money, I got some self-tapping stainless steel screws and went to work. Because the car is so low to the ground, just getting a drill underneath the inside edge of the pipe was tricky, and I've never wanted access to a car lift any more than I did this morning. After several failed attempts which took a lot longer than I expected (including one that initially worked great until the baffle shook loose and the rattle came back with a vengeance on my test drive), I finally got the desired result - specifically, the screw caught solidly on the inner baffle and tightened everything up. No more rattle!