
Originally Posted by
Mozarts Confutatis
I think it'd be possible. Much harder now that there are Aurors guarding the Prison, rather than eyeless Dementors. Because now, the Aurors can easily check who is coming and going much more thoroughly than Dementors ever could. Plus, an Auror is unlikely to be fooled by an Animagus.
As for Sanity, I doubt any of them really kept it. Bellatrix was insane to begin with, and Azkaban can't have done wonders for her temperament. No doubt, it made her worse, but I think the DE's were so confident that they had done the right thing that it served as a kind of mental barrier against the long-term mental effects of the Dementors.
I do hope that helps you!