Gouvernorat de Tataouine Travel Forum

I'll be staying in Djerba during the 1st half of July 2008. After having discovered the Ksar Ghilane oasis last year, I would like to "push" further into the sand dunes this year and I'm looking for any advice about what I have in mind: around 4 days, departing from Djerba in 4x4 to Ksar Ghilane, the Hwayhat Reched lake, Bir Aouine and El Borma (where, if my information is correct, the highest Tunesian sand dune, Zemlet el Borma, reaches 250m). Sleeping under the stars would be preferred.. Is this idea crazy? Has anybody any experience in that area? Has anybody any advice to share (including related to the price)? Thanks in advance.