How does Huck's dressing up as a girl help to establish his independence as a character/

Ah, his willingness to dress up as a girl means he's gotten a bit more daring and is ready to depend on himself to a larger degree than he depends on others. Going back to town, dressed as a girl or not, exposes him to people he doesn't want to see (at least not yet), but he's willing to take the chance to get the information he needs.