BAPTX,
Private party RV sales will very often be on Craigslist. To search a wide area of Craigslist, we use searchtempest "dot" com.
Searchtempest is not perfect, but it will really help to sift through the dozens of Craigslist "cities" within a range that is desired. And, just like Craigslist, it is free to use.
Best luck