FYI the Airvan was flown out after a replacement engine was fitted. Presumably some tracks were worn by 4x4 to ensure the surface was suitable prior to takeoff.
When I had dinner with the CP & her boss last year they said it was lifted out from the lake by chopper. Maybe it got a new engine at Willian Ck and was then flown to Horsham for full inspection.
I've spent quite a bit of time on salt lakes in that region, including recovering a few 4x4's that broke through the crust. Making tracks with a 4x4 prior to takeoff will make things worse not better. Applying weight to the surface brings up moisture and makes the crust weaker. You can stand on a salt lake and put weight repeatedly on one spot and have the surface turn from hard to quagmire.
None of the lakes in the region have been fully dry for years. Lake Gairdner has the thickest salt crust and the Dry Lakes Racing Assoc has cancelled its event for the last 2 years (might be 3). Things are looking optimistic for speed week this year (next week). Check out their photos on facebook.