This isn't quite what you're asking for, but at our company, we handle this with an EDX message from application that updates the database (or creates a flat file, or whatever). I don't know all the details, only what I write in the IBM Mainframe JCL, and what I put on the QlikView Publisher side to respond to the EDX message.
This might be a bit less efficient, but you could kick off the Publisher task frequently during the night, and have it read in the end-flag. If it isn't set, exit the script. If it is set, do the load, and then... I guess update the database using a macro triggered OnPostReload? Does that even work? I thought I remembered that trigger not working in a server environment.
Not really my area of expertise, I guess. Maybe it's a place to start. Maybe not. Hopefully someone with a more thorough understanding will come along.