Cleaning EPDM Rubber Roof

Sure, if you know how to use one and aren't concerned with reducing the longevity of the material. It's pretty much a known fact that EPDM sloughs off the outermost layer as it ages so washing intensely only moves that process along quicker.

Some folks have an unusual situation with their parking location, trees, birds, etc. so washing is probably a good thing. If you store your trailer out in the open, there is really no reason to wash the roof.