Well that's your choice. But if you match the oxidized color and then you ever buff or sand it back to the "real" color, you'll have light
colored patches that don't match.
But if you plan to keep the trailer in the oxidized condition, then you might want to match that. Then I suppose you would want to use "flat" paint
also, to better match the texture.
When you scuff the area to be painted, it will probably come back to the original color... but then if you are painting
over with flat, "oxidized" color, I guess it will all match up in the end. I've never done that because I've always buffed/compounded/sanded to remove the oxidation.