What if you were to just install fans on a case that's designed to be fanless? Wouldn't that theoretically provide more than enough cooling?
Hell, I bet one of these [URL=http://www.thinkgeek.com/computing/accessories/5dee/]USB fans[/USB] would do the trick. I use 'em to cool down home theater components, because my Directv box has a USB port.
Of course, that still means you're really just blowing hot air around.
What if you ducted the AC to the trunk, but not directly into the case? Would that still cause condensation?