Those thermal pads looks ideal, seems like a very easy solution. One thing that worries me is if the IC were to come lose after some time, that would lead to thermal runaway very quickly unless I include some circuitry that monitors the temperature. How well do these pads stick exactly? Can I trust them?
About the clips, I found this: **broken link removed**. I'm not sure if that particular one fits TO-220 packages though, but it shows what I'm looking for. I have no idea what these are called though, I can't find them on mouser.