There are scam artists out there. And there are good people out there who would have no intention of defaulting on a loan, but due to unforeseen problems they end up not being able to pay anyway. And even though you have legal documents showing they owe you money, good luck collecting if that person can even pay their other debts. And by then the RV may not be worth anywhere near what you initially sold it for.
Not a good idea unless for some reason you feel you want to finance the loan and you can afford the potential loss.