CURT 57003 LED Trailer Light Adapter, $23.99 on Amazon, free same day delivery!
Works great and the Prodigy RF Brake Controller is good too.
I have the .75" rise ball mount, but I think the front end of the Airstream is a tad high, so I am going to switch to a straight 0" ball mount. BTW, the manual says that the only allowed ball mounts are 0" - 0.75" RISE. No drop mounts allowed. I think the straight through will be good.
First trip of around 50 miles averaged 660 Wh/mi.