Great question! The reason we have a hike in every week or a ski is just to make sure your joints and limbs get a bit of a break from running almost everyday. I think hiking uphills and jogging downhills for your goal sounds good. You have to listen to your body, maybe you do the longer hike day as a run and do a shorter run day as a hike just to break it up a bit.
As for skiing it is great cross training! Again, I would listen to your body and maybe put that in once a week. Instead of a hike you could ski or do a shorter day skiing. Of course you are going to want running as the majority of your training so you don’t de-train you running fitness. Hiking and skiing will keep your aerobic fitness up though so don’t be afraid to do one of those activists once a week.
I hope that helps!