What the seller should have is their loan documents. The loan company can tell you the best way to handle the transaction. Usually an escrow service is a form of insurance as they handle the money and payment of the amount due to the finance company and then transfer a title or bill of sale to you.
In my state a camper is not registered with the DMV. It is sold like any other piece of private property. What you want to avoid is having the owner not pay off the loan and the company deciding to repossess the camper. Not clear though if this can even be done with something like this.
If it is a good deal and the camper is in good condition then it is worth the effort to close the deal.
Most people, outside of Congress and Wall Street, are honest so I would not assume that there is anything amiss.