Making cloaks ammo-based rather than cargo-based has been sitting there on our to-do list for a good while now.

There are a few "technical difficulties" preventing this from happening, and one of the more visible ones is that even though we can easily define a new ammo type and assign it as cloak fuel in the plugin, the game itself does not support actual cloak ammo, so the ammo type will not be highlighted in the purchase screen and even though every ship can buy it just fine, those with cloak would still see it as grayed out "unusable ammo", and since that list is automatically sorted based on the type/price listing, there's no way of making it appear on top of the list and still use it as a moneysink.

That, along with a few other issues is why we don't have this already.