**Update**

As your description, your test suite has already provided a good level of granularity, but when converting them to automated test it gets a number of dependencies (prepare data, object .. etc). My suggestion is that you can do the dependent steps directly in DB. 

About the granularity, we just convert test case to automated test, so it will be the same level of granularity as what your test suite has provided.

**Original**
Do you or your team have permission to access database ? If yes, you can prepare pre-condition data directly in database

 - Write some store procedures to setup pre-condition step.
 - Run these setup on Test account.
 - Create a job to clean everything on Test account each day.