The Curt # 13554 Class III hitch would work perfectly on your QX70. The Thule # TH9058 Camber 2 bike rack would be completely compatible with the hitch, and your vehicle. When installed, you should have about 13 inches of ground clearance which is enough that any sort of raised adapter isn't necessary. Actually, Thule doesn't recommend using an adapter, anyway.
The rack includes an anti-rattle hitch bolt, but a lock is available separately as part # THSTL2. I've linked to an install video... view full answer...
After reviewing the attached photo, It appears as if the 2015 Infiniti QX70 in question has the Curt Trailer Hitch Receiver part # 13554 installed. Unfortunately, none of our aftermarket trailer hitch receiver manufacturers (Curt/Draw-Tite) are able to confirm fitment on vehicles with an aftermarket exhaust system. view full answer...