Hello MelyMuniz,
Take the idea of adding the USS Nimitz to Ship Simulator;
the problem is that VSTEP must ask the US navy to add their ship in this simulator. But since this is a simulation mend for peace simulations, there is a low chance of the ship being added to SS.
Also an important factor, is that there are some people sinking the ship and put it on YouTube in most cases, so I don't think any shipping line or navy likes to see their ship sinking (can also mean hatred to them).
As for a submarine; I think that won't be a good idea, since the environments would need a full underwater interior which will be a huge graphic consumer.