WIF, That is a great post.  You can bring all the good stuff for safety, be smart on the trail, and not thinking for one small thing can ruin trip, as Kanoes can testify with the wood chip in the cornea.

You can play the "what if and what should I bring to be totally prepared"  when packing, but once out in the woods it is one hundred percent the thinking thing that will avoid issues.

I would also advise as Jimbo noted to stick not only to portage trails, but obviously use them where they begin and end.  We all know running rapids is dumb, but trying to go farther down or up the slow moving river to avoid portaging often leads to bushwack, turn around or other problems, as I and others can surely attest to.