You would have to be pretty unlucky to puncture the floor on the cape trip. Having said that I did puncture my floor on the return trip but that was due to a blow out of the tyre at 110 kph just past Port Augusta in SA.
Kitchen wise absolutely no issues or the fridge inside. Just make sure you tape up the vent behind the fridge as the dull dust and water will get into the cabin through there. I had mine permanently taped up during the day when moving and took the tape off once camped for the arvo.
With the fridge just ensure you latch the door closed before heading off. I forgot a couple of times and found the door had opened and things had fallen out but nothing of major concern.
Thank god for that
Don't forget you will be crossing with a sandy bottom and your trailer may flex.
Mark
And that is where you will have the leaks if the seals don't have enough pressure on them to stay sealed.
Feel free to ask if you need more info.