Hi thanks for the query
The complaints of cracking and popping for long time in your knee could be most probably due to old injury
to the knee. Considering the present age of 50 years there could be problems of wear and tear which is giving discomfort to the knee. The complaint of weakness while going down hill may be due to degenerative tears in the ligaments of the knee joint. I advice you to consult orthopaedic surgeon
who could advice you further management. regarding the wilderness trip you can carry on after advice with your doctor, who can prescribe you basic analgesics.