I just bought my Proton in July and it wasn't paid off. But it will be difficult to find someone willing to cooperate. It is quite tricky, but my situation was a bit unique. But I will tell you how I went about it... I got a loan for the max amount I was thinking of purchasing it for. (Mind you I was in Cali and the VX was in Arizona, I hadn't looked at it yet, and the bank that held the title was in Colorado Springs). SO I flew out to AZ to give her a looky and to start negotiations to drive her home. I test drove her... all was good, a little scuffed, but good. We went to a UPS store to get a contract notarized stating basically, I give him $X to purchase the vehicle with the VIN etc... and he will overnight the title to me as soon as he receives it from his bank. etc. To ensure the money was going toward paying off the VX I had my money directly wired from my bank to his bank in CO Springs, to ensure the payoff. The bank said it would take about 3 days to get the title out. Once I received confirmation, I gave him the balance of the deal. Not even a week later I had the title in my hands.
This is in a nutshell, of course. It wasn't easy finding a UPS store anywhere around our area that had a notary on duty... they were all on vacation. I think we stopped at over 7 locations before we found one. It was an adventure that's for sure. But it can work out, if you and the buyer are really motivated! Communication is key.