Never clean before a trip but like to get it clean as I end or approach the end of a trip. I clean the front of the RV after a days travels to get the bugs off but could not care less if I drove in the rain and it got dirty, it's just dirty. I will head out the next day just the same. I might find a truck wash along the way if there is no chance of more rain but, if not, I will arrive just as dirty as I left.
There is a reason for the wax and there's an even larger reason for the travel. Travel for the adventure and not for the next door neighbors approval!