A friend of mine drove a Perth-bought troopy around Australia, then through Africa to Europe. Diesel, quite indestructible. the only thing that failed along the way was the A/C condenser i think.
Absolutely terrible driving around town in Melbourne - way too big and cumbersome to drive (manual too). So i’d only consider one as a second vehicle. The roof top tent is great, i wouldn’t plan to sleep in the actual car though, especially when travelling - much quicker to set up a little sleeping tent if you have kids around.
His was within your budget but extensively maintained and only used on expedition trips by a swiss nature photographer. He’d fly to Perth, do a trip, park it at the mechanic and fly back to Switzerland. No expenses spared - one in a million buy really.
I couldn’t think of a more suitable vehicle to explore Australia with - just expect to spend a bit more than your budget on a well maintained one?