Interesting idea Shane,
I did a little research, and -- if you have a SQL Server environment available -- invite you to consider using our Workfront Snapshot solution to export your current data (or even use our sample file, to test), then import it into SQL Server, then push it into GCP.
If that path works well, you could then rinse and repeat whenever you want to refresh/add a new slice of the data (since our Workfront Snapshot includes a timestamp on every table to support such data slices); or if you prefer, to at least use the result as a base in GPC against which you could then roll your own API scripts to sync data thereafter.
I'm interested to hear how you make out -- good luck!
Regards,
Doug