One concern would also be the software. What's good for truckers? CoPilot is the only one which advertises ability to do truck routing. But just like you commented about the TomTom map quality, the CoPilot may not be satisfactory either (non-Navteq maps, proprietary CoPilot data). Some truckers have said CoPilot isn't really good at the truck-specific routing anyway (so why bother).
A trucker will not want to just enter a destination, hit a button, and drive. He will want to check the route if it's okay for a large vehicle. Some software may not be that easy to use to pan map, zoom out, etc. And you are designing this for a person who may not be so passionate about technology. What's left? A printed road atlas for truckers only, perhaps?
Many truckers use Microsoft Streets & Trips on their laptops, but I'm not sure how comfortable with a laptop would you friend’s dad be.