I am not and expert on knee pain, but I will share something from personal experience. I used to do long-distance running. I instisted on continuing training for a marathon in spite of persistent and worsening knee pain. The bottom line--I messed up my knee to the point that I can no longer run again! In other words, I hope that you can solve the problem to the point that you can still go on your tour. However, given a choice between a tour and permanent damage to your knee, I would take care of the knee and forget about the tour, even if you lose money on it.
What's worked for me in biking is to start off a training regime very slowly with regular short flat rides at first, and build up gradually from there, only adding hills later on after my knees and legs start to build up their strength . However, knee problems vary and yours might be completely different than mine. Hopefully somebody here will have a better solution for you that won't require you to step back from your training.