You might also take some footage of a general background scene. Imagine that you had just turned the camera around and filmed a few minutes of what was in front of the truck - trees, buildings, ?. You could drop this into the windshield with Track Matte Keying. I *doubt* that it would need to be exact, unless you also make a big deal of showing that scene (in front of the truck) later, and even then, use that footage.
Sounds like you need to know how to do some 'simple object removal'. Check the link -
This is a great tutorial site and this tutorial will solve the p[roblem I'll reckon.