Curt used to make one for the Passat, but you might have had to trim a hole in the bumper but I could be wrong. It's been a while since I considered one.
Hitch for wagon is different from one for sedan, so bear that in mind.
EDIT:
This is what I remember seeing available from Curt although on RA these seems to be 'out of stock' ATM.
This one is for the sedan....
Steve