You could use one of the 2 fan aluminum drive cooler that bolts to the bottom of the hard drive. I think Vantec is the usual brand you'll see. Take off the fans and use the rest as a passive heatsink.

One quick comment, re: stealing. In the US, if you are delivered something you did not order, you are allowed to keep it. That applies to the postal service, but since it's a federal law, I would imagine it applies to the other delivery services also. But I bet nobody will willingly tell you that. w...

I know you said you didn't want to heavily mod the cases, but have you considered putting a blowhole with a low noise fan in the top? That should get rid of a lot of excess heat, while not forcing the PSU to run it's fan faster. It shouldn't be that labor-intensive to pop a hole in the top.

Aren't they just the same PSUs, but with different fans?