You need volume, not mass.
If a ship gets big enough it doesn't need armor as armor anymore, reduce your mass as much as you can (but get a lot of volume).
At least that's how i roll. :D
The funny thing is ogonite as "best" armor material is best cause it's the super dense... on big ships i prefer to inflate my volume with tons of trinium armor.
So mass is not equal volume??? All this time I thought it was lol