Oh, and I just have to vent about one participant who was a "survival instructor" or maybe primitive lifestyle instructor who had hard time making useful cordage when he had TWO bags around him.
Shows like this often have hidden rules. Maybe he wasn't allowed to shred the bags.
The nakedness is a gimmick, although a fairly effective one. I do watch this survival show when I don't watch many others, and it's not because the educational content is superior. Generally it focusses on the trauma and what they did wrong, rather than what they did right. Letting them have two tools is actually one of the few points of interest, because we see how much difference different tools make. It seems if they have a fire-starter, then they can get a fire going quickly. If they don't, then it takes many days if they manage it at all, despite their skill with bow drills etc in their home environment. They don't know which local woods to use, and if they don't manage it the first day they quickly become too tired and hungry to work with the patience it needs.
The lack of clothing is a factor for exposure, both to heat and to cold. One guy was incapacitated by sunburn for his first week, and they all struggle with the cold and rain. Also, they all seem to underestimate the effect of insects on morale. No clothing means getting eaten at night, and no sleep. That said, wearing a small swimming costume wouldn't much effect the experience.
Returning to the subject: it's a show I wouldn't consider going on because they don't seem to take enough care over the participants. The crew all leave the island at night, and if there's an emergency it takes them hours to react. Emergencies are likely because of the lack of food, lack of protection and generally dangerous environment. You don't have to go behind the scenes to see how bad it is.