WWII Sizaire-Berwick Wind Wagon - photo

[tonyfoale]

Interesting that the engine is tilted down at the front. That will create a downward component of the prop force, which will press the vehicle down on to the sand. That would increase wheel drag and the tendency to dig in. In sand, that is the opposite of what you need, it would be best to try to float over the surface, especially with those narrow tyres.
That is assuming that the drive is only from the prop. The machine does have a normal engine compartment at the front, maybe that is a relic of the base vehicle or does it retain wheel drive capability? If so, was it intended to use wheel drive and aero drive together or was wheel only for use on hard surfaces?