Fat tyre biking is well established with the Surly Moonlander, Speedway Cycles Fatback and other mountain bikes running enormous 4 inch wide endomorph tyres. These bikes are great on snow and sandbut if you add a load then they obviously begin to suffer.
Enter the fat trike. On sand this vehicle would be ideal. Desert sand where the big problem is carrying water. With wide forks and a 4 inch tyre on the front of, say, a kona steel frame and a trike conversion on the back running two giant fat tyres you could for around a €1500 convert a conventional mountain bike into a desert crossing monster.