If you want to restore what you have without using tricky epoxies or special paint, retr0bright and plastic polish will restore what you currently have.
Retr0Bright will work inside the trailer, but requires a UV light, available online if you can't find one near you.
Here's a link
to examples and the recipe. 12% hydrogen peroxide, or concentrations higher than the usual drugstore stuff, can be bought at beauty supply stores.
Plastics can be polished up, but I have no experience with that. Google will be your friend there.