The inability to use cellular for the communication is the showstopper.
If you could use air cards there are a number of solutions on the internet, like GPSGate.
For the two other vehicles you could use the tracking function of something like
SPOT II. It sends the position data via satellite, so as long as there is a good view of the sky there's a decent chance you'll have fairly current location data. But the catch here, again, is you still need an internet link in your vehicle to access the internet for the position information transmitted from the truck.
I'm not sure if there is a totally satellite-based solution.
...ken...