I second the post about learning to do the deed with water rather than paper. I was a volunteer in a developing country and had to learn to adapt to local custom.

The world can be divided into two broad camps--the wipers, who can't believe the people would actually wash their bums with water and the left hand, and the washers, who can't believe that people would actually rub paper against their bums and call that clean.

Both camps have their advantages and disadvantages, but I'd say the washers have the edge when it comes to surival situaions, except perhaps in the desert if water is scarce. Oddly enough, it's the desert people among others that tend to be washers, go figure. ;-)

It's easy to carry a bar of soap, which you should probably have anyway, not as a luxury but for good hygiene to prevent disease, to deal with the consequences of the washer camp.