You are right that the data needs to sit in an extract to use so that piece is right. You could write a script and delete all local extracts each day/time I guess.
The second question - 'display an interactive page' ?? Could you elaborate on that? Also I am going to move this to the Web Data Connector area.
I don't think such a delete script is going to fit the bill.
What I was referring to in "display the interactive page to the user." is the interactive part of a web data connection that lets you set parameters on the WDC before it retrieves the extract. Like this interactive page for example: webdataconnector/earthquakeMultitable.html at master · tableau/webdataconnector · GitHub
What I need is for the users to be able to set these parameters on every viewing of the reports that rely on the WDC data. And it's not looking doable unfortunately.