Django-filter: Allow to override retrieving of a queryset in a FilterSet

The title may be a little bit confusing. It would be nice to have a generic filter method which is called everytime queryset is retrieved and filtering for fields is applied. Yeah, I can override qs property, firstly get filtered queryset and then apply prefetches. But _it's not clear if this may have some side-effects and the data passed to filter is safe to access._

There's my use case.
I'm filtering a queryset by a M2M relationship (as in queryset.filter(items__field="foo")). However I want to get prefetched items filtered by that field as well.

In other words my filter looks like this:

# In my filterset
def filter_items_by_field(self, queryset, name, value):
        queryset = queryset.all().filter(
            items__field=value,
        )
        prefetched_items = Prefetch(
            'items',
            Item.objects..filter(
                field=value,
            ),
        )
        return queryset.prefetch_related(prefetched_items)

# In my vieset
def get_queryset(self):
        queryset = super().get_queryset()
        # This should be applied everytime
        prefetched_items = Prefetch(
            'items',
            Item.objects..filter(
                another_field=some_value,
            ),
        )
        return queryset.prefetch_related(prefetched_items)

A single filter like this works as expected. However, I may have several filter_items_by_* filters + I need to apply same filtering for queryset from prefetch for all filters. And multiple filters aren't a problem, because they're mutually exclusive in my case. But a filter + generic will cause an exception.

The point is that I can apply only one prefetch for the same lookup. So, in my case I'll simply get an exception.

I have a temporary workaround for this problem: all filter_items_by_* performs mandatory filtering on prefetch.
And in filter_queryset (after filtering was applied), if items aren't prefetched (what is bad since I'm inspecting queryset protected attrs), I apply prefetch with the mandatory filtering. But there should be a better way to deal with situations like this.

I hope my example is clear enough.