I wish there were an easy fix/plug, too... I have literally never turned on the rear wiper in almost 12 yrs of having the car.
The only time it was ever on was when 'Juanted' drove the hell outta it at a meet at his house, lol!
Same for the CEO's Hyundai Tuck: the rear has never been on in three years.
No rear vision problems, here.
GL, D