If you're still leery of paying for the vehicle up front without any guarantee of receiving title, then you may want to consider using eBay's vehicle escrow service. You pay the purchase price and the escrow fee (roughly 1%) directly to the escrow service instead of the dealer. Once you receive the title and agree that all terms of the sale have been met, then you release the funds to the dealer.
All eBay sellers are required to accept the escrow terms for vehicle sales. Yes, it does cost more money, but it also affords you additional protection in the event that the vehicle is intentionally or even unintentionally misrepresented; e.g., an appliance that turns out to be non-functional.
Although I've never actually used the eBay escrow service, I have used an escrow service when purchasing aircraft on eBay. The process for purchasing an aircraft is astonishingly simple compared to buying an automobile or an RV - the seller fills out a half-page form (8050-2) that basically requires only the seller's name, address, and a signature block. The signed copy is then sent to the FAA after the buyer provides the funds. Adding an escrow services costs only about 1/4 of 1% and includes a title check at the front end of the process before any funds are deposited.
For the record, I live in southern California and purchased my Roadtrek Agile SS new from a dealer in Texas. I FedEx'd him a cashier's check a few days in advance, then flew to Dallas to pick it up. Texas has a provision for a 30-day temporary registration of vehicles purchased by out-of-state buyers - the only downside is that I had to pay the roughly $100 Texas motor vehicle inspection fee. The MSO followed in the mail about two weeks later, permitting me to register the vehicle in California... and pay a buttload of taxes and other state-mandated fees as well.
Although I didn't use an escrow service in this case, I did verify that the dealer was indeed bonded for the state of Texas. The most difficult part of the entire transaction was convincing the California DMV that I purchased the MH out-of-state in order to save $20k and NOT to circumvent California's smog laws. Sheeesh...
