On my old unit I used Rainx wash and wax. Worked very well. I also sprayed it straight on the front of the trailer and let dry before each trip. used a 1 gallon sprayer I kept in truck bed. Made bug removal a snap later. I did have to re apply after driving through rain. Haven't washed my new unit yet, but will probably use the same. Be sure to use hot/warm water and change it often if it gets dirty. I used a cloth mop too with an extension pole. Best soap to use if your going to wax separately is Dawn dish soap. Its also great for the black tank before use.
Hope this helps
