I will be skiing in Montana in January but hoping to sneak away at least one day for a snowmobile tour in Yellowstone. I'm curious what lens people would suggest for this type of trip. I will be carrying the lens in my backpack and have both a D500 and D800E at my disposal. I presume most of our wildlife sightings will be bison, but I'm just not sure what focal length I will need. I have no interest in hauling my 300mm, f2.8 just for this one day outing. I have an old 300mm, f4 AFS and my 70-200mm, f2.8. Don't own an 80-400mm, but would consider renting or picking one up. Seems like a 200-500mm would just be too big to bring but could also buy and rent if advised. Thoughts?