Can I configure Django for Unit tests with restricted view on unmanaged databases?

Question

We are a small team, trying to work with Django with a restricted access to a futurely unmanaged PostgreSQL database (i.e: only views and stored procedures ; no access to any tables) for security reasons.

1. We tried to give (within Postgre) the user external_test the rights to create any tables inside his own schema on external, and to use the following settings (settings.py):

...
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    },
    'external': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': 'postgre_db',
        'USER': 'external_user',
        'PASSWORD': 'password',
        'HOST': 'integration.project.net',
        'PORT': '5432',
        'TEST': {
            'NAME': 'test_db',
            'USER': 'external_test',
            'PASSWORD': 'password',
...

2. Using simple passing unit tests (project/app/tests/test_views.py):

...
class InternalTest(TestCase):
    database = ['default']

    def test_something(self):
        pass

class StoredProcedureTest(TestCase):
    databases = ['external']    

    def test_one_procedure(self):
        with connections["external"].cursor() as cursor:
            cursor.callproc("some_procedure", [42, ])
        pass
...

3. If we try the first one with ./manage.py test app.tests.test_views.InternalTest
   → ok

4. If we try the other one with ./manage.py test app.tests.test_views.StoredProcedureTest
   → circular dependency issue
   (ImproperlyConfigured: Circular dependency in TEST[DEPENDENCIES])
   probably because it's skipping the configuration of default

5. If we try both tests with ./manage.py test app.tests.test_views:
   → permission denied

   Creating test database for alias 'default'...
   Creating test database for alias 'external'...
   Got an error creating the test database: permission denied to create database
   

   (Django try to create a database test_db as the user external_user)

We don't really get what Django is trying to do and how to properly configure it.
If we give the rights to external_user to create their own databases:

• the database test_db is created by external_user
• the schema of default (sqlite) is created in test_db of external (postgre)
• the schema of external (postgre) is not created in test_db

Questions

1. Is django able to handle this ?
2. What are we doing wrong ?
3. What is the point of specifying a user external_user for TEST if in the end django is using the normal user external_user ?
4. Why does it write the schema of default in test_db ? Is there a way to create only models of some apps in it ?
5. Why isn't it able to create the schema of external in test_db ?

I hope it was described enough. Thank you in advance for your responses =)