In conjunction with the factory tow hitch receiver, any feedback on a good ball and ball mount? I am likely going to be pulling an Airstream and believe it's 2 5/16.

 

You can't go wrong with a CURT hitch receiver and ball. They are all available on Amazon. You will need to confirm the ball size, the 2 in square hitch receiver size, the 7500 Lbs. tow limit, and the drop and length of the receiver.

I have attached below a PDF file from the Defender manual describing the allowed receiver drop and length.

Enjoy !!