Nice. Green or Red?
It'd be quite a hack job. It'd try to keep the interior's function, and leave the glovebox alone: you'll need it.
Your best bet is to slip it under the dash.
Fans are essential. It can get quite hot in the summer here in Houston (up to 40 deg C), but the plus is that there's always enough sun to power a solar cell
As for mounting the HDD, Panasonic uses gel paks in their rough line of laptops, which have a magnesium allow case. These things are actually designed to be dropped from a height of three feet (!)
In this case, I think I'd go with a rubber band suspension, at the very least.