How to make entry.category to be instance of CategoryProxy? See code for details:
class Category(models.Model): pass class Entry(models.Model): category
This is an open Django issue: #10961 (Allow users to override forward and reverse relationships on proxy models with ForeignKey fields)
You can work around it by resetting the fields in question after you define the proxy models:
EntryProxy.add_to_class('category', CategoryProxy)