I'm doing the carnivore challenge along with Wifezilla and I agree, it's a challenge getting fat up there! Eggs help - 1 tbsp butter per egg works out to about 80% fat. Forget how much protein though.

Ever read The Optimal Diet by Jan Kwsensomethingski? (note:that is not his last name, I just can't spell it) His idea is that we should eat 1g protein and 3-4g fat per lb "Ideal" body weight.