Hi again,
There is a piste from Douz to K.Ghilane and another from K.Ghilane to Douiret, near Tataouine, nice to go in one side and out the other without using the old pipeline piste which has now been surfaced. Either of these tracks have plenty of places to pull into the dunes for an overnight stop, there is little to no traffic after dark. Tembien is worth a visit, a little south of K.Ghilane, there is a flat top mountain (hill) that you can walk to the top of using a "sheep track", not a journey to do alone though, 2 vehicles at least.
It is as you say, relatively relaxed, in that area. There is a wild camp at Termersa (pic on homepage of my site
Home page) and the waterfall is worth a visit. You can get a nice piece of Amathyst for a couple of packs of ciggies and some cans of lager, from the guys on the stalls at the top rather than actually down at the falls. The camp is the opposite side of the main road, you will see the tracks.
Kebili has a camp site, not up to much but a place to stop for the night, and a shower if it is working.
Douz, the best site is in the town, the toilets and showers are nearly spotless. Difficult to access in the morning cos the market is in the street but after 3pm no problem.
We will be going in April 2009, been at Christmas 2004/5 and 6, last year me and the wife back-packed to Douz etc. If you should want a hotel, just for one night, maybe, the Mars 20 in Douz is excellent value, breakfast is a little sparse but the rooms are lovely, and V. cheap.
I have 2 very useful contacts in the area if you need them, 1 in Douz the other in Bechni, about 30km south of Kebili.
I think I've also got the gps for Rommel's bunker somewhere.
Have a good one, oh, if you get the time, Aghir on Djerba has a place to camp, right on the beach, toilets and showers "work" that is about it though.
Ps where you getting the tickets for the ferry, I can tell you where to get them cheaper, about £650 for car, two adults and cabin with windows.