As a hunter from Washington state who also has a degree in Exercise Science, I feel I can give you a pretty good idea of what an ideal training regimen might look like.
First thing, get strong. A lot of hunters shy away from lifting weights and I have no idea why. Emphasize heavy compound movements like squats, deadlifts, pull ups, and presses and you will put yourself on the fast track to building some seriously practical strength for hunting. There is a sweet spot for hunters where both strength and endurance are at a maximum, leading to improvements in cardiovascular activities as well. Find that spot, it's unique to everyone.
Second thing, train your energy systems, not just your muscles/heart/lungs. Your body utilizes a variety of fuel sources (fat vs. carbs) and energy systems (Phosphocreatine system, glycolitic pathway, etc.) depending on the kind of activity you will be participating in. Walking, running, sprinting, and lifting each use very distinct energy systems, all of which must be targeted in an effort to improve systemic efficiency. In my opinion, variety is key here; run, hike with a pack, and bike a few times a week. Go fast on short hikes, slow things down for long runs. MIX IT UP! Gradually, you will increase your work capacity to the point where you can increase the volume, frequency, or intensity of your training to continuously force adaptations in your body.
I am a fan of the mindset that practice/training should not just simulate the real thing, but be much more demanding, so that when the time comes to hit the mountains and fill your freezer, the last thing on your mind is your body.
Hope that helps and thank you for your service boss!