OPFOR is AIM-120D, which is just barely shorter-ranged (somewhat less dV, but somewhat lower drag, too) for equal launch conditions. 'Missile truck', by the very virtue of being thus loaded (drag, reflection), will get itself within opponents' engagement zone. At this point trucker himself is within a2a engagement - and thus consequently isn't really a pass anymore, just a team engagement.
It's just a normal range for modern MRAAMs. To properly forward pass a weapon you'll probably need ~1.5 the reach, yet from a lower expected energy state(if we are to carry many weapons), yet at a similar time to target.
This naturally leads to a big weapon, or something else entirely (say, the truck carries flying pylon-type CCAs instead)