Donna,
We have family members that think we are hicks, but our solution works for us!!
We purchased a 6X12 piece of astroturf from the local hardware store for about $15. We hose it down when we get home to clean it off. We don't stress over it when it gets dirty, and it keeps the dirt out of the trailer. If it is wet, we roll it up and bungee it to the back bumper of the trailer.