Day 5 is going to focus on cardio. The backcountry is a test of endurance more than strength so you need to be sure that you can meet the challenge.
Do 25 minutes of HIIT for one of the following exercises:
Speed-walking on treadmill at max incline (sprint intervals should be walking at a speed that would be more comfortable to run. This causes your body to work harder because you are forcing it to do something less efficient by continuing to walk)
Do 2 minutes of slow warm-up
Then do 14 sets of 30 second sprint and 1 minute active rest
Finish with 2 minute cool down
Remember that HIIT is a combination of sprints and active rest. Active rest means you keep moving, but at a slower pace. Sprints should be done at full intensity.