Draw the outline of the ship and then put like a little tiny box inside it and say 'crew here' and then post it and
Damnation, somebody remembered I came up with that concept.
Since when has the "need" entered the equation?
We don't "need" freespace at all 
A Fenris occupies greater volume than a Nimitz by like two or three times. It is entirely possible to spend years aboard a carrier and not see all of the ship. You could take a week just visiting every compartment for a couple minutes.
Dunno about you, but unless there's something that really, really demands deck plans to make it work, I can think of easier ways to go insane. Greebling a borg cube, perhaps.