Erasing deleted files (Eraser won't do it)

Most of my portable applications are setup to use a TEMP folder located on my UFD. I use Eraser in a batch file to wipe what gets left behind in that folder. There is no way to wipe the files that have already been deleted by the applications (which is most everything unfortunately).

The process I'm forced to follow, is to run Recuva to restore the deleted temp files, and then wipe them. Recuva can't work from the command prompt and requires admin rights. Is there a way to wipe deleted files (or undelete files) without admin privileges, without knowing the name of the files (just the folder location) and from the command prompt? I'm trying to avoid wiping empty space, because that's typically several GB.