I'm not completely understanding why you're needing an adapter, and why it'd need to reach around the bumper. Which hitch are you using? I'd recommend using the Curt Class II receiver hitch, part # C12054.
I'd recommend simply using a cargo carrier that's designed for a 1-1/4 inch receiver like the 20x48 Curt cargo carrier, part # C18110. Using an adapter will lower the tongue weight capacity (maximum amount of downward force that can be safely applied to hitch) by half. You'll avoid this... view full answer...