On the inside of your trailer above the refrigerator, running from the counter top to the ceiling, should be a plastic (ABS I believe) chase. On the exterior, where that chase hits the interior ceiling, should be a cap about 1' long that is basically a rain shield. If the chase and the cap aren't there, then the PO removed them, and in order to put in a trailer friendly refrigerator, you will need to re-invent/install both components.
Others will have other opinions.
My 2c, and worth every penny.