Thanks, I hadn't heard of retractable trailer tongue / drawbar - makes sense.
Don't see Airstream trailers over here, but they remind me a bit of some models of Kimberley trailers (but they don't have the rounding at the rear).
Best Australian Off-Road Camper Trailer | Kimberleykampers
Those 3 wheeled motorhome shapes look good, but not sure I want to build a full custom motorhome from scratch - chassis, drivetrain and all. I might be a sucker for pain, but not that much!
