ace, I agree with you about the need to study how a functioning rigging actually applies, and you definitely didn't 'cheat' on your rigging for the brig Irene; you did the darn right thing by actually following an existing rigging plan! Now, as for the 19th c. ironclads, even if this one is considered a pure AU-vessel, there are rigging plans available on the web, in the form of real ships' rigging. Those can be very useful. Also, klagldsf is absolutely right that often captains chose to 'de-rig' their armored vessels, if for no other reason, to free acrs of fire for their guns, prevent debris from falling down on the decks in a possible battle - but there were also a great many old-fashioned 'sailing-ship captains' who disdained the notion of propellering their vessels with the aid of steam. Rather they went to, sometimes, extreme length to continue their sailing practices; sometimes so far that they simply forgot that they also had steam engines onboard, resulting in inadvertent collisions and other mishaps!
Edit: Yes, if you have a rigging plan, study it and copy! No harm in that, but beware still of adapting it to your ship's needs!