The so-called "Small Set" or Hadada-repro set is now buried beneath a sand dune - so no wonder you could not find it !
Added to that the fact that locals used bits of it for fires so it is no longer complete.
Maybe in 10 years time it will slowly emerge from the other side of the dune as the dune moves slowly forwards. I'd like to be around to see that.
The main Mos Espa set still exists and although weathered, only a few bits have collapsed and it is reasonably free of dunes. There are one or two areas where the sand is building up.
Both sets are within 500m of each other. They are located quite close to Camel Rock (another popular tourist destination) used in The English Patient and as Darth Maul's landing site. Located NNE of Nefta and NW of Tozeur near the edge of Chott el Garsa (sometimes Gafsa).
West of Nefta are the Homestead Igloo and Craters and the Dune Sea.
East of Tozeur is SW Canyon and Raiders of the Lost Ark's Tanis Excavations.