If the daypack is too small to carry rain gear - get a bigger ruck!!!!!!
You listed the S6 so I assumed (you know what they say about ASSuming things) you had selected the S6 for this exercise.
You stated the environment was timber so I would want a large chopper for use in constructing shelter and making fire. Therefore the SYKCO for the job is the DOGFATHER <img src="/ubbthreads/images/graemlins/thumbup.gif" alt="" />