OK my suggestions.
1st, get a decent mount for the Toughbook. Panasonic do a Vehicle mount Docking unit (CF-WEB273) as do LED and Kodiak. You can mount it in the back out of the way powered up by a LIND auto adaptor.
Get hold of a separate screen - I am using a CF-VDW07 wireless screen which is driven off a Wifi card in the Toughbook. It's a touchscreen unit with an 8.4 inch screen. Mounting this in the front with a Arkon 18 inch Swan Neck mounted to the floor. This takes up far less room than mounting the Toughbook up front - far less to crash around in the front if it all goes badly FUBAR.
Get yourself a Bluetooth PCMCIA card for the Toughbook or a Bluetooth USB dongle (if going the PCMCIA card route use a Billionton one as it fits in the 3rd (internal) PCMCIA slot on the CF-28) and fees up the other two for using for the WIFI card for the screen.
Get yourself a Bluetooth GPS receiver and mount it on the dash with hook and loop tape. If it is a SIRF 111 then it will get a perfectly useable view of the sky, plenty of satellites and quick start up.
Get Ozi Explorer or the GPS program of your choice with topo maps.
You now have a fully useable in car PC for using for GPS, MP3 music or anything else (when you are stopped of course).
You could even if your Toughbook has the option built in, use the WAN Wireless capability (CDMA etc) and get online while you are wheeling and use something like Google Earth - could even be used for tracking purposes.
it's taken me around 1 year watching things come up on ebay but eventually have everything I want for my Toughbook CF-28 and have probably spent a total of about $1000 on everything including the Toughbook, Wireless Screen, extra memory, 160gb Hard disk, Arkon Mount, Vehicle Docking station, Wireless Screen interface card, rubberised backlit keyboard.
Good thing is with the whole setup it can be out of the car in seconds so no need to leave it all in the vehicle when it is parked up and liable to theft.