We went out there around 1 month ago, as a day trip from Alice.
Road out to Maryvale was great - though given the clay, would be very slippery it wet. After Maryvale, it was very corrigated, we dropped out tyres (more for comfort than anything), but the traction was good, didn't engage 4wd at all. The sand dunes I've heard people talk of where surfaced with Gravel? There are still signs as you head out there that this is an extreme 4wd track and to engage 4wd as you enter the park - but we didn't find anything like it.
Depends on the camper trailer I guess, ours would have been fine, but as I said, corrigations were pretty bad.
Chambers Pillar in my opinion was sensationan and well worth the trip.