We paid cash. With something that depreciates as rapidly as an RV it makes no sense to finance it and have the added interest expense.
If I was going to take out a loan it would be for no more than 5 years. You want to have enough of the principle paid down so when it comes time to sell the RV you can at least breakeven and not be in the hole with the loan amount still owed. I see this with the people that spend $60,000 or more on a diesel truck and find that they owe the bank $40,000 3 years later when they want to sell it.