I'm probably one of the only people who enjoys trading! Mainly because I suck at PvP!
I love the whale, its already easy to pirate, if you get stopped you have to pay.
So more cargo and less armour wouldn't effect the pirating side of things much for that ship, but for others it benefits pirates more!
Just yay more profit!
I would think that it can be done, if armour upgrades can, theres no reason why this shouldn't be possible