We did it towing the Avan in 2011.  Most of the road on the WA. Side was OK but that also means hundreds of km of corugations in places. Then loose sandy stretches as well as good graded sections.   It all depens on what you and your rig consider as "rough" 

We found the NT side was by far the worst at that time.   (Actually the Mereenie Loop was worse still)

And of course where the graders have not got to.

We would do it again, but some of our companions on that trip suffered damage from not having the van prepared for  gravel road travel.  We have a presurised van to prevent dust getting in and do a lot of gravel roads.  That trip for our van included the Plenty,Donaghue, and Savannah Way as well. With no damage and little dust ingress

Recomend you check

Fridge properly secured, all van seals on doors, widows and vents actually sealing. Block off fridge vents (fridge off) the dust will break your heart if it fills your van. If your drawers and doors are not reinforced they fall apart.

Make sure the stuff in your fridge like bottles and heavy stuff will not damage the fridge as 6 hours of corrugations and vibration can smash polycarbonate shelves and smash bottles.

Secure you micro wave and its glass plate.

We had a great trip as the weather was beutiful and the scenery as well. Wish we had spent more time on the trip as it was magnificent.

Let your tyres down and keep the speed down. It was the speed kings in our party who suffered the damage.

Hope you have a great trip, and remember to get the "Permits"  online.

Regards 

Mike.