I've had good success with Mr. Clean Magic Eraser on the fabrics of all my camper awnings. After cleaning your camper fabric, try using a Mr. Clean Magic Eraser as a follow up. Make it good and wet and simply wipe it over the material and let it dry.
I have found the chemicals in the Mr. Clean Magic Eraser prevents black and mold growth. One cleaning on my awnings a year and I never have mold or black (dead mashed bugs are a different matter though.)
Anyway, it's something you might try. Remember, with Mr. Clean Magic Erasers, never scrub a non solid or painted surface. Wipe only, no hard pressure. (If in doubt, test a small area first, see what happens).
FYI, when we our tent camper (pop-up), I'd clean the fabric, then when dry, spray the dickens out of it with tent spray sealer. It seems to help, until I discovered the Mr. Clean, and then I never had problems again.
Good luck.
