@Murdock Can I change the preload ammo boxes you can order via combat supply?

Is there a way to use an eventhandler to do that? I'm just beginning to understand the things you can and cannot do, so I'd rather ask than spend several hours trying to make something impossible work.
The idea is to make an eventhandler, so that when a supply box of a specific type is spawned (means: ordered via combat supply) the eventhandler deletes all things inside and adds specific things back to it. So when the Player gets to the box, it just contains the things I want to be in there, not the vanilla stuff. To not overwhelm the Players, I'd blacklist some boxes in the logistic/c2 module or whitelist those I want them to use.
Would that be a possible solution?

@highhead ad. 2. think there is a way with overwriting staticData.sqf but you would have to define new classes of boxes with custom content in the description.ext though and im really no config expert.

Where do I find that staticData.sqf? Or do I have to create it myself like the init.sqf? If I create/define a new class of box there, will it be available via logistics and/or zeus/Editor too?