Firsly, congratulations on purchasing a caravan. May you have as many great trips as we have had - plus more.
We went to Longreach last year and came back probably the way you would go up. If we were to go, we would go Dubbo. Burke, Cunamulla, Charleville. We have stayed at Charlieville. If you go there, a must to see is the "Cosmos Centre" to watch the stars. They are an observatory that open both day and night, and you see such a beautiful display of planets and stars during the night session. Another thing to see is the "Bilby Education Presentation". This is where they show you beautiful endangered Bilbies they are breeding. Then head north to Blackall, Barcaldine, then on to Longreach. Enjoy your time at Longreach seeing the Stockmans Hall of Fame and the Qantas Museum, and if you are not to tired, please drive the 173kms north west to Winton. At Winton, you will find a little place called Lark Quary, where there is the first set of dinosaur footprints fossilised in the rock. It is actually a stampede at the edge of the river and is absolutely facinating. If you have the opportunity when travelling, book in at the Caravan Parsk (a few days ahead as so many travel this way) and see the Bush Poets. They perform at the parks and normally are only a few dollars to see, but well worth while.
Hope this helps and happy travels.