what if you did something like this

```python
class CacheBackend(object):
    ...
    @staticmethod
    def setup_model(model):
        model.add_to_class('pending_objects', PendingStateLogManager())
```

Then in your models.py

```python
backend = import_class_by_path(settings.DJANGO_FSM_LOG_CACHE_BACKEND)
backend.setup_model(StateLog)
pre_transition.connect(backend.pre_transition_callback)
post_transition.connect(backend.post_transition_callback)
```

This would make adding attributes to the log model as pluggable as possible. It also doesn't involve putting backend-specific code directly into any other part of the library.