I live in Cornwall, UK, and have owned and maintained an Airstream in the USA for 14 years. My working life was in law enforcement.
I would not do what you are planning. There are so many pitfalls. The condition of the tires and brakes, the lack of weight distribution, the lack of compatibility of the electrics, the unknown state of the frame, the illegality of the brakes, are just the start.
I would transport the Airstream on a low-loader as close as possible to the farm, and then drag it slowly with the tractor the last part of the journey. You can then sort out all the issues at your leisure. I believe you will be far less stressed, and much safer, and you will not risk prosecution and/or a serious accident.
Nick Crowhurst, Excella 25 1988, Dodge Ram 2500 Cummins Diesel. England in summer, USA in winter.
"The price of freedom is eternal maintenance."