Belt Bay would be the worst place on Lake Eyre to attempt a landing. It is the deepest part of the lake; is often one of the last places to dry out when the lake has flooded; and has a very thin crust. Far better would be the south-east corner which is the last place to flood and has a thicker salt crust. As previously mentioned, it is where Donald Campbell set his world land-speed record for that very reason.
In 2009 when I was at the Lake, you could see where people had tried to drive and walk onto the surface of the lake at ABC Bay which adjoins Belt Bay. You could clearly see where they had broken through the salt and revealed the underlying mud. I also spoke to tourists in the pub who had attempted to walk on the lake surface. You could tell who they were by the mud caked on their shoes. They all told the same story about breaking the surface salt crust. It does get thicker the further out from the shoreline but very doubtful that Belt Bay would support an aircraft.