Can you provide a concrete example? I would assume if you wanted to decouple the persistence model from the domain model then you would need to write a separate domain model in Django since the domain and persistence model are tightly coupled.
I'm not very familiar with Django thus my ability to provide relevant examples using this particular framework is limited.
However I direct your attention to the fact that Django docs make it very clear that to them in general each model maps to a single database table. That's quite Spartan even for an ORM, and obviously the point of a domain model is to model a problem domain, not to model the database.
