The trailer "hitching noodle" ©. 8/1/2013
What you see inside: (*)
Voila!
* (Aiming base of the rear window wiper to touch the noodle, cut to 36", provides the centering location, and the top of the noodle touching the window & reaching a specific line on the window's defrost wire grid indicates when the car should stop backing up.)
Dan S, webweaver