As someone who studies and to a small degree work in survival, it's a passion of mine. I agree entirely that end game survival is far too easy and I believe I have a solution too that will have a positive impact on mid game also. Early game is also too easy in my opinion also.

My idea is this, the more weight one carries (having less stamina) increases hydration consumption. it makes more sense because the more weight you carry the more you'll sweat the more you'll lose water in your body, plus the warmer your gear a well affects this. Predatory animals having parasites is an interesting idea but I don't believe the best direction to balance end game. Needing to carry water with your character must be a must end game. Having to always look for water the more loot you have on you creates a more realistic survival experience, which also effects, of course, blood regen.

Concerning parasitic meat I believe should be a regular concern at all times in the game. IRL hunting animals, this is a real concert should to find a diseased animal. BUT, just like buggy pumpkin pests, all animals should yield meat and have the potential to have between 0-40% of that meat and fat be infested (with a texture similar to the bugs on leaves) worms in the meat. So when cutting up a cow, lets say 40% of that meat could be full of worms making the meat inedible. Making survival at all stages harder and definitely impacting late game as well. Both faster dehydration later and the potential to yield less consumable meat will create the type of survival I believe you're looking for.