All desert spec land cruiser come with narrow sand tires on split 16" rims. I'm referring to the 70 series..
This is the factory choice.
In sand, you need the length of the tread more than the width. So when you deflate, you get better floatation. No doubt the width does help but it doesn't affect as much as tread length (tire height).
Vehicle weight and tire load range along with tire pressure are the first thing to impact performance. deflating a light truck to 20 PSI will return less affect than deflating the same car with lighter load rating on the tires and at the same tire pressures.
Narrow tires will have less rolling resistance and less wear and tare. Also less fuel consumption. There is really no debate with narrow vs wide.
In terms of height. 33s would be the max size I'd run on any light load vehicle. In Saudi, they run 750R16s all day long because its the best compromise between clearance and performance.
On my general purpose cars, I prefer 255/85s. In my 20+ years of experience, they have been the best all around tire for a little bit of everything use.