Bells and whistles are just the particular features relevant in your particular case. I don't write scripts for other people as a rule, on the grounds that it's your mission not mine.
one in front of it exactly to within 3meters.
even if there is a person standing infront of the humvee.
That is probably impossible, due to the collision detection routines. If not, it is still a seriously advanced scripting problem. I would recommend 9 hummers, 9 drivers all in the same group, and a few move waypoints with setbehaviour safe.
I wrote about working with, not against, the game engine in a thread the other day.