Do an internet search for RV Financing and you will get lots of hits. There are several big lenders who specialize in RV loans and they will handle the arrangements with the dealer. Beacon Credit and Essex Credit are two of them. Bank of America also has a large RV financing arm - they may be who your dealer uses. Good Sam has an arrangement with one of the big RV lenders too, so check the Good Sam web site too. And if you tell your dealer you have a better rate from another lenders, he will most likely match it so he can retain the commission he gets from whatever lender he uses.
And of course check local banks and credit unions.
A "good rate" will depend on your region, personal financial history, the amount of the loan and the term (length) of the loan.
Oddly enough, you can get better rates for larger and longer loans, e.g. $100,000+ for 15-20 years. Your $25,000 loan puts you more in the arena of a typical car loan and you may find that car-loan rates is what you get. In that case, a credit union is often the best bet.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL