Hey DuncanB,
The track to Wedge can be pretty gnarly at times and a good 4WD is essential. Take great care, check out the tides and avoid the beach track if the tide is high. The beach track has claimed many cars and the 4WD recovery tractor is really really expensive and gets even more so depending upon how close your car is to being covered in salt water. I've heard him charge up to $1000 for a tow out, cheap if you drive a Sahara or a BMW X5.
The inland road is long and rough as hell and you still have to navigate the dunes at the end of the track just before Wedge.
Have fun and drop your tyres to 15psi and you shouldn't have any hassles.
Good winds,