I used that bondo stuff "black again" or something like that.. it was AWFUL it was basically black paint.. you can still see remnants of it on my fender after i dont even know how long... probably been a year now.. I think that crncnn also used it on his cladding with not very good results

I do remember one person saying they liked it though.. I could see it working well to make your cladding really dark permanantly if you used like 3-4 coats to be sure its even, it was really streaky to put on

imho i would just look for the purple mcguires tire shine and use that once a month with a few touch ups