There are numerous lendors specializing in RVs and they often beat any local rates. They are used to dealing with remote purchases, even private sales, via phone and fax, so no problem working a deal through them either. Some examples are Beacon Credit, FUN, Essex and Dimen are a few. Bank of America is a major RV lendor and they deal through a number of finance brokers. Just do a web search (e.g. Google or Yahoo search) on RV Finance and you will get many choices. Shop around and see what reates you can get.
If you are aGood Sam or FMCA member, the clubs have arrangements with a lendor to provide decnt deals on financing, but I would still shop around a bit.
RV dealers get a nice commission for arranging finance and generally have high rates unless challenged to meet another lendors offer. If you tell the dealer you have an offer for financing at 1-2 percent below his rate, they can usually match your deal, giving you the conveninece of dealer financing without the price penalty.