With that amount of output, you're going to have to eat a ridiculous amount if you're going to hope to gain any mass. Really, I'd suggest eating as much as you're able to get down between those workouts. Heavy sugar or hi-gly carbs might not work well for you, but you're going to need to get calorie density from something. Whole milk, ice cream, lots of nuts, rice, whole grains, red meat, whole eggs, etc. I wouldn't even worry about blocks if I were you, but that's just me.
Nutrition and eating clean are one thing, but the other thing to consider is your digestive system; you're not going to be exactly getting the opportunity to eat paleo foods when you're in ranger school. I'd suggest getting your body used to the kind and types of foods you'll eat there (probably really calorie-dense) so that you don't have a digestive shock when you show up. If you've ever eaten super clean for a while and then re-introduced "normal" foods and seen how it affects you, you probably don't want that kind of system shock when you enter Ranger school.
I'd worry less about the macros and blocks and more about getting tons of cals, making sure you have plenty of protein and quality stuff in general.