As a contrast to Marcantoine77's snow, I'm just returned from a drier- and warmer-than-normal Prescott, Arizona, where I ran some backcountry stuff in my Gen 2 Cayenne.
It did fine off pavement and, as usual, did a stellar job on pavement during the 2500 miles of highway travel required for the transit to and from home.
I have a few things to share, none of which is rocket science, but the information might help some. First, I found it really handy to remove the second row outside headrests (I'd removed the middle one early on). Having them out kept the front seatbacks from fouling on them when the second row seatbacks are dropped. But the other, probably bigger, feature is that with headrests gone, the second row footwells become a much better and more accessible storage area. (These headrests don't pull out easily. There's a diagram showing how to do it on the internet.)
Some 958 owners might have missed that they have a not-readily-visible 12V power port tucked way to the front of the front console-side passenger footwell. Because a cable from it to the dash won't have to cross across controls as they do from the console power ports, it's a great spot to get the power needed for a dashtop mounted GPS tablet.
I had occasion to want to spend a night camped inside the truck. Rather than go with a cot, I thought I might be able to figure out how to make a decent sleeping platform that was both easy to install and remove. Because the second-row seatbacks don't fold flat, the key was finding a way to make a platform level from front to back. It turned out to be easy for me, as one of the $29 Rigid 22 inch Pro Organizer tool cases I use for recovery gear was exactly the right height to level things out.
I used a piece of 1/2 inch Baltic birch plywood for the platform. I started with a 30 x 60 inch sheet (often on sale at Rockler stores) and cut 5" off the side to match the width of my sleeping pad. However, as you can see from the photo, you could go up to about 28-29 inches and still fit with the passenger-side seat up.
I'm not exactly tall, but still more than 60 inches. There's room for nearly six feet of length with the front seat back. But the exact maximum length will depend on the driving position, including seat recline. Obviously, moving the driver's seat forward would allow for a lengthy platform, but then the platform would need to be hinged or consist of two pieces that lock together so that it could fit when there's a driver. Alternately, if you didn't have a passenger and could fold both seatbacks at night, a very long platform could go on the passenger side instead.
In my case, though, the quick, dirty, and cheap solution was just to find another case I was carrying--in this case a Gall's tactical case used for my clothes--of about the right height to hold up the last foot of the inflatable pad. Since all it has to do is support your feet and calves, it doesn't have to be anything particularly sturdy.
I should also probably make reference to the somewhat zany quilted mats covering all of the cargo area:
It's a custom-fitted mat set available through Amazon that fastens to the carpet on the sides and seatbacks with hook and loop fasteners. It does a nice job of protecting the cargo area from the cases and other hard/pointy stuff carried back there. I'm pretty fond of the set and wrote a detailed review of them that's posted on Amazon:
https://www.amazon.com/Worth-Mats-Coverage-Waterproof-Porsche-Cayenne/dp/B0797WB63B.