Elbow Grease
The best way to keep a trailer looking new is frequent washing .
and keeping it under a carport , 3 sided shed , or garage .
i am a carguy in a car club . all of my cars are shiny and detailed all of the time .
But for a trailer , what really works is just to wash my 2002 Komfort ( ordered new ) after every trip , without exception .
For the trailer I use a 9 " soft bristle brush on a 6 foot handle and palmolive dishwash liquid .
I pour a 5 gallon bucket of HOT water , dip the brush in it , and lay a stripe of palmolive onto the brush face , then wash a section . spray off .
I use the same method for the roof and the awning . A washmitt takes care of the tighter spots .
I used to wax this trailer with inexpensive polish like NuFinish .
Now I use "ICE" because I just need a protectant .
Trailers are big . I have found that by using the easy method I will maintain the discipline of washing every time .
For my cars I use a clay bar , mostly McGuiars products, only soft wash mitts ( no brushes) , and so forth .
One word answer , so popular = Elbow Grease .