The basic ideas of Emerson's Self Reliance are 1) One must trust oneself, and 2) The ideal is to exist in the present, as nature does.
These two basic beliefs are quite prolific in Huck Finn. Huck has always had to fend for himself since his father is a drunk and his mother is not mentioned anywhere in the book. There is a brief period where Huck is taken in by the widow and her sister, but he "escapes" from their "sivilizing" in order to smoke and be out on the river. He takes life as it comes, and doesn't stress over too much. He is absolutely of the "go with the flow" of the river school of thought. Huck and Jim deal with things as they crop up. They do have a plan, but as things change throughout the book, they adapt their game plan as needed. They certainly lived in the present.
Huck also struggles with his conscious where Jim is concerned. He is upset that he is helping an escaped slave to run, but he also recognizes the friendship that has developed between them. Huck even decides that if loving Jim and allowing him to escape to freedom means Huck will go to Hell, then he'll just go to Hell. In a sense, he is trusting himself to make the right decision.