Why not advertise right here too?
We listed our previous RV on every free site available to us (there are a bunch of small ones besides RV Trader and RVT).
The RV sold to a buyer who found us thru Craigslist. We wanted max exposure.
The sale is done (or should be done) in-person. How the buyer finds you is irrelevant.
Expect there will be "tire kickers" that spend their day wasting your time. The only alternative is consignment or trade-in. For that, you gotta decide if you want all the sale money, or if your time is worth the difference the dealer will take.
Just ignore the obligatory e-mail from the middle-east sheikh who wants your RV, sight-unseen and will pay you more than asking price, if you just return part of his check for more than agreed - or similar scam offer.