The 48 Laws of Power, by Robert Greene.
Law 18: Do not build fortresses to protect yourself-isolation is dangerous.
Probably more relevant pertaining to one's regular social circle and career. The Prince's kingdom and court.
Backpacking in south America, you are not really going to isolate yourself. I would recommend insulating yourself from the half-wits, drunks, druggies, (gentusa en general)
I kind of agree with Tate's view on the likes of people who (not all but a lot) backpack to the likes of Thailand (and South America) you don't want to become infected with their poisoned mentality...
So perhaps...
Law 10: infection: avoid the unhappy and unlucky.
Watch your drink (be it agua or an alcoholic beverage) at all times (I don't mean stare at it like a lunatic, just don't let it out of your sight) as slipping a mickey in your drink and being relieved of your possessions (and maybe more) is something you would want to avoid.