If you do it somewhere cold you loose the chicks in homemade bikins, which would certainly decrease viewership on some level. IMO cold is the toughest climate. You can live in the heat if you cover your skin and have plenty of water but living in a frozen tundra requires such highly specialized skills that you would be really limited in possible contestants unless you just wanted to send people out to die.
A few years ago a saw a movie called 'Series 7: The Contenders'. I noticed that it has been on some of the Showtime or Stars expanded viewing channels on my digital cable. It also might be available through Netflix. Anyway, in the movie they randomly pick six people's names in a geographical area (like a town or county). They go to these people, tell them that they have been picked for the show, and give them a pistol. The contestants get 24 hours to buy more weapons, make their house into a bunker, or whatever. Then they hunt each other down. Last person alive wins for that week. The people have no choice whether to participate or not, if they want to ignore it or abstain then inevitably some other contestant will show up and off them. As completely disturbing as this sounds I think we are almost at a point in our degenerate culture that people would watch a show like that it if it was aired.