The Lipton meals top out at almost 600 calories and are great tasting, easy to cook right in the pouch and at $1 apiece, they blow Mountain House, at $4-6 each for about the same calories, away. I add a tuna in oil pack for dinner and I get about 1000 calories. Add some GORP through the day at 1000 calories, 2 oatmeals and a couple granola bars in the morning for another 500 calories, granola bars and peanut butter for lunch and you can easily get 3000 high potency calories. For about $6 total for the day. You can also cook the oatmeal in the pack. Just use hot water, not boiling. A coffee mug is the only "pot" I carry and I don't do dishes. I use a MSR Pocket Rocket stove.
You won't be gaining weight but go into the hunt a few pounds over your peak conditioned weight and you will have some spare energy to burn. Drink lots of water and get sleep. I sleep over 8 hours a night. It takes lots of oxygen to convert fat so rest is critical.