Wow. Some interesting ideas.
Dont worry yourself too much. We did it last year and honestly, I'd be happy to take an old Honda civic across there. Personal choice would be a 1979 Corrolla but I'm just giving you an idea how easy it is.
There are a heap of people out there too. The biggest problem is the distance to a major town should you do something major.
The only time I engaged Low Range or the Centre Diff was on the Beach north of Broome. Oh and Pigeon Hole at Elquestro. We were the only people to go into Pigeon Hole and it wasn't that good to look at but worth it to get away from the crowds.
I think just about everything else would be 2 wheel drive accessable. I imagine in the old days you could drive to the water falls and maybe that would have required a 4x4 but these days you have to walk a damn long way to everything.
The worst thing that could happen is something breaks and stops you travelling. We met a guy at Mitchel Falls in a new Jeep. He said the last thing on his mind was his suspension (just giving you an idea what type of bloke we were talking to). He had down a shock and it was costing him $2500 to get one flown up from Perth.
I think the going rate for a tow at Dunmara was $3000 or $5000 with a camp trailer.
We didn't see of hear of a single person getting bogged, just plenty broken down for what ever reason.
GRR is easy as. I know the corrugations vary through out the year but we went at the end of School holidays, a time know for it to be the worst.
Kalumbaru road on the other hand was the worst corrugations I have seen in my life, hands down. Both myself and my mate had brand new shocks. I was running Bilstien 7100 with external cnasters and he had new Tough Dogs in his 100 series cruiser. You will hear people say you will find a right speed where your wheels are just boucing on the top of each corrugation but that doesn't quite happen as the corrugations aren't constant. It's like 2, miss 1, 3, miss 2, 4, miss 2, 2, miss 1, 4, miss 3. All over the place. That's what breaks things.
As for recovery gear. Your not going to need a hand winch unless you think you are going to find a place that know one else knows about and given the number of people out there, that's not likely. Same for max trax, There's plenty of people around that will tow you out.
Tamini Rd services a couple of mines so it's just a Dirt Highway really.
Happy Days.

