cargo turrets
mass 1000
adds 10 cargo to whatever ship its equiped

you could also have capital cargo turrets
mass 100,000
adds 100 cargo

would be targetable and if destroyed drop said cargo

+1 I like it

Variation: Towable cargo pods.
eg: Marauder visuals

Maybe different sizes, capacities, prices, license requirements ...
Of course physics should apply and ship performance impacted appropriately.
Maybe only certain "cargo oriented" ships can use "towing kits". Or light ships can only use small versions.
Maybe only available to non-cap ships. Or maybe Cap versions are rather expensive in some way.

I believe there is a rule allowing only one suggestion per thread.
Aside from that, I support both suggestions.