If you haven't already resolved this, I would like to undertake a POC with you utilizing ELTx LoadItAll. You'll know within 10 minutes whether or not it will work for you. My sense is, it's probably the type of tool you're looking for. http://www.eltx.co/LoaditAll.html
We have begun using Clover ETL to create Tableau TDE files directly instead of using Excel or other intermediaries to get data into Tableau. Only issue when converting is I had to recreate all my calculated fields and at the moment those fields are returning NULL values even though the same calculated field worked before. We are excited to be able to auto connect Clover with Tableau.. saves a ton of import/extract time.