Live in rural South Australia so will most likely be the Flinders Rangers (rocks and long dirt roads) and down the South east way (sand dunes). So nothing crazy to start with
I have never lived in SA but have done a lot of touring in the Flinders Ranges, around Roxby Downs, the Oodnadatta Track, Birdsville Track, Strzelecki Track, Innamincka, Dalhousie Springs and Mount Dare.
That was in our current car, a 2003 Hilux, that we have owned for 14 years.
Prior to that I drove over the Nullarbor four times in 1972 and '73 in an EH Holden. The road from near Ceduna to the WA border was unsealed. One thing that stood out while driving over it was the number of discarded tyres, buckled wheels and pieces of exhaust systems lying along the side of the road. Excessive speed on some of the rougher sections would be have been the reason for that.
In addition to to that, my wife and I have driven (solo) over many of the not be so well maintained Beadell tracks in other states plus a few other remote tracks. All of this has been on standard specification tyres running on the hand book pressures.
The suspension in our car is stock standard. The protypes that Toyota thrashed the living daylights out of in our central deserts also had the same suspension. It passed their tests so they put it into production just like all the other manufacturers do.
There is no need to " upgrade" it unless you want to carry an excessive load. That lifts the car and makes it look good but it is still overloaded, or incorrectly loaded, resulting in the Outback vehicle repair workshops doing a roaring trade during the cooler tourist season months fixing bent chassis, cracked/broken rear axle housings, sheered off wheel studs, cracked wheels, overheated engines and so on.
If the people living in those remote areas had to modify new cars with non genuine parts to make them suitable for their conditions, they would not buy them.
Keep your weight and speed down in those conditions and you won't have any problems.
Regarding sand driving: if you drive to an area just to drive on sand and nowhere else, you should find a set of partially worn street tyres will work a lot better than AT or mud tyres.
Way back in my RAAF days I spent many months on a beach with huge sand hills trying to clear an old bombing range of unexploded ammunition. Our Landcruisers used sand tyres. They were smooth with no tread except for four narrow straight groves to displace water if they were to be driven on wet sealed roads.
As far as width goes, they looked only slightly wider than the standard specification 7.50x16 off road tyres.
We must have got stuck every now and then but it must have been a rare occasion because I can't remember any.