I spoke with my contact at Yakima who said that all of their adapter sleeves, including the Adapter Sleeve For Yakima HighLite and DoubleDown Ace Bike Racks # Y8890342 that you referenced, are made of metal. view full answer...
I'd recommend the Curt Class III Trailer Hitch, part # 13354. Curt manufactures their hitches in the USA. Draw-Tite is an American owned company, but their hitches are manufactured in Mexico.
If you'll be using the hitch for towing purposes, you'll need a few more parts to complete your towing system:
Trailer wiring harness with 4 pole trailer connector, part # 118424
Ball mount, part # 2923
Trailer ball, part # 19261 for a 1-7/8 inch or # 63845 for a 2 inch. view full answer...