I think the problem would be chloride ions in the steel, they would rust the steel quicker than you could look at it!
Five years in a bath of running water or a week in a furnace i believe is the way to rid it of the chloride, putting a tank in a furnace with HE shells would be interesting!
The slapton sands Sherman has been coated in bitumen to stop it degrading any more.
It would be great to bring them up and a real challenge to preserve them but worth it in the long run, the only other way is to leave the history to disappear.
A big glass tank of water with a Centaur in it would make a great exhibit.