i think that the cargo unit should cost 3, move 2, capacity 5 i.p.c. with no defense.
i think that buying the unit’s would stop excessive funding of other national power’s, and the capacity would mean that even though the unit’s might be more numerous, they have a cost which would be factored into the descision to send them, the cargo can be distributed to a territory that has an i.c. and can be used at that i.c. until the cargo has all been spent. i.e. a territory with an i.p.c. value 2 get’s 15 i.p.c. worth of cargo, build’s 2 tank’s at the next purchase unit’s phase, save’s 5 i.p.c., which can then be used at the next purchase unit’s phase to buy 1 tank.