My rig never leaves the driveway without a wash, whether it looks dirty or not.  I use any car wash with wax in it product I can find on sale.  Long extender pole with soft large brush I bought from Wal Mart six years ago for $20 and still going.  To dry I use a squeegee on a broom handle to get most of the water up above reach level, then I wrap a cotton towel around it to get the rest of the high spot water. I don't care much for the micro fiber towels so many people like.  They don't seem to soak up much water and leave streaks or smaller water marks.   Wax once a year with Nu Finish with touch ups, especially the front with a quality spray on wax like EagleOne's Nano Wax or just cheap dollar store spray furniture wax.  Before season I used Mop n Glo, two coats on my fiberglass roof.  I do not wash is during the year figuring rain takes care of that.