Wait, we can uninstall Dawnguard after making a save with that data? I was under the impression that the game wouldn't allow us to load that save up without the DLC.
As far as I know you will get a warning saying that the save contains data/content no longer available and will ask you if you wish to continue. It will basically remove all Dawnguard content and you can continue on as if the DLC isn't installed.
There was a bug in Oblivion where players would enter a DLC house, save, remove the DLC, reload the game and then they would be in some bizarre testing area for the game.