I found the best way to handle this is to put the custom SQL code into Django's migrations.
Django and South (which is the predecessor to Django's own migration framework) both provide commands to create custom (i.e. empty) migrations. The code for creating database views or functions can be put into an empty migration and will be run whenever a new installation of the project is migrated or the test suite is run.
A tutorial on how to use custom migrations for database views with South can be found here. The syntax is a bit different in Django's own migration framework but the documentation about RunSQL
explains it all.