Get a bike and drive slowly between the lead jeep and the truck. Once the jeep is far away, hit the breaks. Get off the bike and equip a close-range weapon. Shoot the truck driver and rear escort only. There will be troops from the first jeep that will get back at you, take them out. Go home and drop off the truck. Then kill any remaining enemies pursuing you.
Images: <military1><military2> <military3>
The image featured at the top of this post is ©The Legend of Heroes: Trails of Cold Steel III key art.