yep - welcome to my 2yrs of work on a carPC !
I used RoadRunner F/E, as it was by far the best/easiest to use IMO. Worked really well.
BSOD's were just due to vibrations/knocks IMO. I had a laptop hdd because a 3.5" would definately not take the environment (I tried) - but even the laptop hdd struggled. I started to move over to solid-state CF cards, but you can't (or at least couldnt) boot directly from the CF slot on the mobo. Then i tried a basic O/S on CD, so no hdd, and that didnt work too well either, unless you were stationary when you switched it on. And then the boot time was too long.
I eventually got my PC to go in/out of hibernation in about 15seconds - which was pretty good.
I spent ages making the boot sequence quicker, removing bits from windows to make it more stable/quicker etc.
I used a 6 channel JBL amp - 4 channels for the individual car speakers, and 2 channels for Subs in the boot. (or 1 x bridged sub) - worked well, and u could get a remote lead for it to control volume in the car, but i just couldnt get hold of one.
Just gave up in the end. Sold for a slight loss, but i had fun so no worries there.
Mine all went into the boot - with very long leads running down either side of the car (keeping phono's away from the power leads etc, shielding)