which event in the book tortilla curtain will you consider as the best depiction of the central conflict that Jose Navidad faces?

I'm not sure if you consider it an event, but Jose's skin color plays a major factor in the story. Because he's described as a light-skinned Mexican, I might infer that he is half-white, and half-Mexican. This makes me think back to another famous character of mixed race from William Faukner's Light in August - this guy's name was Joe Christmas.

Get it? Joe Christmas. Jose Navidad. They both have some serious identity issues. Because they are not really accepted either North or South, they develop some serious anger management issues. They both become rapists.

I think Boyle is making a major point with Jose Navidad about people trapped betweeen two worlds with no way to escape.