Question regarding purchasing an RV from private seller

I am currently in the process of purchasing a travel trailer from a private seller here in Louisiana and would appreciate any advice on the best way to handle the transaction.

I have already viewed the RV and we have agreed on a purchase price of ~$17,000, which I am prepared to pay outright (I am not financing through a bank). However, the seller is currently "upside down" on their loan, owing approximately ~$26,000 to their bank. The seller would like to use my funds to go towards the payoff to clear the title and release the lien. Also according to the seller the lienholder/bank is an out of state bank that is the dealerships preferred lender

To ensure a clean release of the title in my name without delays, I have a few specific questions:

- What is the most secure way to facilitate this three-party transaction (myself, the seller, and the lienholder)?
- who would i make the check out to?
- Should the transaction take place at the seller's specific banking institution to ensure the payoff is processed immediately?
- What specific documentation is required in Louisiana to ensure the title is properly released and transferred after the lien is cleared?
- Are there specific notarization requirements for the bill of sale or title application that I should prepare in advance?

I am ready to be flexible with the process to make sure this is done correctly the first time regarding taxes, registration, and title transfer. I have vetted the sellers and they appear to be honest people but are just bit unsure on the process as well.

Any advice is much appreciated.

(yes, i am fully aware that owning an rv is a potential money pit)