I realize this is an old thread but, for all of you still searching for a product to clean those plexi shields, I recently found a product. I used it after washing and drying the trailer and it made a nice difference in the way the shields looked.
The product is made by Blue Magic and is called a Plastic & Plexiglass Cleaner and Light Scratch Remover. Comes in an 8 oz. bottle.
"Thereís two kinds of people, them goiní somewhere and them goiní nowhere. Andís that whatís true". -Ben Rumson