Well OP, I disagree with you that carrying "extra mass" around is going to hurt you. Carrying 80-100 lbs on your back is going to be much harder at 150lbs as compared to someone that is bigger and stronger at 170lbs.
But you are the Ranger, so you probably know what is best for you. If this is the case, and 150lbs is an ideal weight, then you'll want to maximize your strength AND performance at that weight.
This really doesn't mean anything that different, but:
Lift to get stronger
Limit the cardio (and in your case, if you do use cardio, take a peformance based approach) Dont look at cardio as a way to lose fat or weight, look at cardio as a way to improve your conditioning/endurance.
In your case, you'll probably need a mixture of HIIT and longer steady state type stuff (Im not saying HIIT is better, but may be specific to some of your requirements)
The key point I would stress is that STRENGTH is going to be top priority for you, and cardio/conditioning will come second.
And a lot of this will depend on whether you are a ranger now, or training to be one, and how long you have to prepare, etc.
Your best bet, is to contact someone that is experienced with training for the military and special forces and see what they suggest (lets just hope they know what they are talking about).
Otherwise, you could train similar to an MMA fighter or a Strongman competitor.......
***And make sure to focus on performance, not having HOT ABZ!