Hey Allan,
For a 2017 Ford Mustang GT convertible there's currently only the Draw-Tite Sportframe Trailer Hitch Receiver # 24928. This is a 1-1/4" shank with only a 200lb tongue weight capacity so you'll need to be careful to not overload it.
If you need a cargo carrier then I recommend the 17x46 Curt Cargo Carrier # C18145. view full answer...