NuFinish (as mentioned earlier) is a "wax" of sorts...another is NuImage. NuFinish can be found at any Auto Supply store, NuImage can be found at VTS
. These will help...but no matter what, it'll slowly start to oxidize again - the moisture in the air (& salt spray from the ocean) will expedite the process. Here in CO, it's really dry and it takes longer to dull.
The good news is, once it's clearcoat is stripped and it's been polished, your trailer will oxidize evenly unlike when the clearcoat fails & it oxidizes with a splotchy look. So it's not as noticable ~