Actually, the KE10 to KE30 Toymotor Corollas had a very similar 'hole in the head'... I will ask my nephew what his solution is to that leaking problem when I get a chance.
As for the 'outback'... Peter was talking about a trip to Windsor, which is on the fringes of our biggest city, Sydney. And he mentioned the freeway, so that meant he was travelling from near the centre of that city, which is full of traffic (4 mill people). Actually Villawood is near Parramatta, a city within that city, to get from Villawood to Windsor does mean a lot of traffic.
The road to Wyong, however, is freeway for the most part. And it's through some of the roughest hills you could imagine, but the traffic along that road certainly flows quickly. It's a 110kmh limit most of the way, and there are a couple of very steep hills.
When you get this truck of yours sorted, you should come pay us a visit, learn about what we have here!