If you have fiberglass sides, there are a couple of options. 1)Use a really good rubbing compound and have it buffed followed with a really good wax. Rubbing compound comes in different "cuts" so depending on how bad the oxidation is, will determine what cut to use. The danger here is taking too much of the surface off and bearing the underneath surface. 2)Wet sand with a 600/800 grit sandpaper, a light buff followed by a good wax. To do it right, you need one of these:
TheseWhat I would suggest is to tow it to one of the local body shops and have their painter look at it and tell which would be your best option. He can tell you what compound to use.
I tell you this based on experience from having owned a paint and body shop. If you decide to paint it yourself, especially using cans, it will not be consistent. In the end, you will be more disappointed in the looks of it than you are now.