We have had a gas V10 and bought a 40ft DP in 2011 and really enjoy it. The only thing I would change if I purchase again is a DP with a side Radiator for easier access to the Engine.
I have sold several vehicles in Texas. As someone said I would go to the bank and make the payment transaction. If the vehicle does not have a lien I would then take the buyer to a court house and transfer the title.