The abillity to place ammo boxes(Empty whitout annything in dem) on the battlfield allowing players to load them up with what ever they want. The once done they can load it into vehicles.
This would include:
Large ammo boxes: Needs 2 man to move them around or 1 using some kind of tool.
Medium ammo boxes: 2 man to just carry them around no need for tools.
Small ammo boxes: 1 man to carry them around with ease.
Tiny ammo boxes: Could hold 1 weapon with some ammo, 1 man needed to cary this at a combat pase.

I dont really know more idea's regarding this feel free to add some info.