So, let's consider the v2.2 point of view

:
- Each character must eat at least 3 Kg of food every day to remain healthy.
- Domesticated animals count as 1.5 times this weight...here we have a philosophical debate, but let's consider that we are domesticated animals...So, a character needs 2Kg of human flesh every day...
- Accordingly to the rules, roughly 30% of the animal's body weight consist of edible meat...So, "standard" group of five characters must consume 1.5Kg x 5 of human meat every day, around 7.5Kg in total...
- For a victim of 75 Kg, the group will obtain about 22.5 Kg of delicious meat...3days of food...
The best...you don't need to do Survival checks. Just wait for the right roll in the Encounters Table.