In case anyone else wanted to upgrade their fulton extraction kit to cargo 2 (for extracting vehicles and containers) as soon as possible in MGS5. You need a transportation specialist, which you can find earliest in mission 10. As you might suspect, you need to save the two prisoners, one of whom is the transportation specialist you are looking for, at the very beginning of the mission before they are executed. Sneak in there as quickly as possible via the left side of the structure, save them, and get out!