DB Permissions with Django unit testing
Don't force Django to do something unnatural.

Allow it to create the test schema.  It's a good thing.
From your existing schema, do an unload to create .JSON dump files of the data.  These files are your "fixtures".  These fixtures are used by Django to populate the test database.  This is The Greatest Testing Tool Ever.  Once you get your fixtures squared away, this really does work well.
Put your fixture files into fixtures directories within each app package.  
Update your unit tests to name the various fixtures files that are required for that test case.

This -- in effect -- tests with an existing schema.  It rebuilds, reloads and tests in a virgin database so you can be absolutely sure that it works without destroying (or even touching) live data.
Disclaimer:
I'm very new to Django.  I must say that so far I really like it.  :)
(now for the "but"...)
But, there seems to be something I'm missing related to unit testing.  I'm working on a new project with an Oracle backend.  When you run the unit tests, it immediately gives a permissions error when trying to create the schema.  So, I get what it's trying to do (create a clean sandbox), but what I really want is to test against an existing schema.  And I want to run the test with the same username/password that my server is going to use in production.  And of course, that user is NOT going to have any kind of DDL type rights.
So, the basic problem/issue that I see boils down to this: my system (and most) want to have their "app_user" account to have ONLY the permissions needed to run.  Usually, this is basic "CRUD" permissions.  However, Django unit tests seem to need more than this to do a test run. 
How do other people handle this?  Is there some settings/work around/feature of Django that I'm not aware (please refer to the initial disclaimer).
Thanks in advance for your help.
David