Thank you

Maureen
I didn't get to read your post as we only got back yesterday from a trip to the centre, but I guess you were asking about the condition of the Plenty highway. We did this road two weeks ago although we couldn't return that way as it had been closed due to rain. It's a very long isolated road and the condition varies considerably. On the Qld. side for many km's it's just two wheel tracks through grass lands. Either side of the border was about 150kms of quiet bad corrugations then long sections of freshly graded road. The only place to get fuel is Jervios station $2.88/litre, you can also camp there $10/vehicle, everything is cash only.
Everyone we spoke to at Boulia before we started had destroyed tyres coming across due to the sharp stones on the road. I lowered the pressures on both the car and trailer and kept my speed below 80kph and didn't have a problem. However make sure you carry at least a couple of spares as you're a long way from help.
We really enjoyed the trip and were disappointed we could not return the same way.

Have fun
Jon