When I (a farang) sold my truck to a Thai, they came to my house, looked at the truck, agreed a price, they produced LTO forms for me to fill in and sign.
They used their phone to transfer the money into my account, my phone sent me a bank message, the money was there.
Mrs.T went with the buyers to the LTO, they came back, LTO wants a copy of my visa, I printed one off, job done, easy....