I have tried a bunch of different cleaners to take off the black streaks from the camper. None of them worked very well, even with a LOT of elbow grease. Then I found this product, actually my camping buddy Tony, told me about this product. The name of the stuff is SCRICHIT. Yeah I cann't pronounce it either, but this stuff works. You spray it on the streak and wipe it off. You don't even have to wipe hard !!!!! But you do have to rince it off well. THAT'T IT.
Here is the web site: www.scrichit.com
I am not connected to this product in any way, so this is NOT SPAM. Just trying to help my fellow campers. If you doubt me go to some of the other threads you will see my name and comments.