Hussar
Legend
I think, perhaps, the best approach is a gentlemen's agreement when creating characters. If you want to run "man vs nature" type adventures, just ask the players not to play full casters. Just don't have clerics, druids, wizards or sorcerers in the party. That, more than anything else, will affect the feel of the campaign. And it will fit so much better for the genre too, IMO. If you have characters dropping spells to solve problems, that's just not very Sword and Sorcery, IMO. Skills should be the focus of the game, not someone's spell book.