Oxidation on Pontoon boat play pen area

[scott&kellie]

Ok so I know i've read that oven cleaner, and the Awesome Degreaser cleaner from a dollar store, I tried both products yesterday to get the oxidation off the play pen area (skirting) but neither worked. Is there another product out there that will take it off. my plan is to get it off and do a good waxing on it to help prevent it from coming back. Any advice on a product i'm willing to try, i've attached a photo (hopefully it works), it's not the best but it shows what I'm calling oxidation or is it something else? thanks again for any and all help.

Scott