Well, galvanic corrosion finally kicked in fully on the Prius. The aluminum heat shield above the cat gave away last week. This is my quick (and hopefully permanent) fix. I also did a very similar fix to the heat shield above the muffler way in the back as the exact same thing happened, corrosion around the washer holding it up.
The fix was to drill two holes in the heat shield and just wire it up tight. I do wonder how long it'll last. I guess we'll see.