According to CURT Manufacturing's website, their tow hitch is compatible with ALL 2nd generation Subaru XV Crosstrek models (North American model years 2013-2017).
CURT Manufacturing - CURT Class 1 Trailer Hitch #11286
They even have XV Hybrid-specific wiring kits available, so I would assume that you could use one of their hitch receiver products.
As for the no-towing policy with the XV Hybrid, I think that's just a case of either they didn't bother to test it, or they found issue with it. Based on the lawsuit-happy stigma these days, I'll lean towards the former, since the batteries add significant weight and may reduce payload and towing capacity.