anand- Nice Touraeg (sp?) Other than lack of sleeping space I wonder why we don't see many of them set up for overlanding
Spare tire storage is a big problem, factory spare is an inflate-on-scene deal which lives under the "trunk" (instead of under the truck)... The rest of the world got an optional swing out tire carrier, but that involves a new tailgate, and modification to hold anything larger than the 255/55/18...
To combat this I built a little storage shelf for the storage area, and while it looks like it kills all my storage, there is a TON of room (virtually the width of the trunk, and just a few inches shy of the depth) underneath to store goodies down the road (second battery, OBA, inverter, etc)
I run a 20mm wider tire than most (most go w/ a 265/65/18), thus my shelf is taller than what others would require, but I think I could still squeeze in above it if I continued it through the rear seat area. The "expedition series" Touaregs (never produced, just a marketing thing) utilized roof-top tents.
Also, when these trucks break, its often $$$$, and they rely very heavily on their electronic systems. Like Nigel said, despite these being normal full production run vehicles (that are going on 8 years of production), LOTS of VW dealerships are absolutely clueless when it comes to diagnosing/repairing them. As well, the aftermarket (for virtually anything, not just off-roading) is very slim; for instance, I had to have my own spring spacers manufactured for a modest lift (instead of the $2k+ bill for the German made 30mm lift kit); of course, only one other T-reg owner has done the spring-spacer style lift; and I can count on two hands the number of off-road/expedition style prepped treg's