With the arms, try your best to get the material over your elbows at least, even though it might be bunched up. What I have found is to actually NOT try so hard to get the material all the way up the arms into your pits like you could with a bigger shirt or an open back. Do some partial ranges of motion in the shirt, board presses working off a three, then two, etc... being your in Iraq, use whatever you can for this eventually trying some floor presses if that's all you can do. If it's absolutely too tough to make any progress, you can try wetting it down some. This works best with denim shirts but may work with poly as well.
Do you have a 50 Rage closed back? If it's closed back, pull the the back of the collar as high as you can on the rear of the neck and pull the scoop of the neck as low on your chest as possible, drag out excess and lock with belt. Then take shoulders and push together like you have tits, yank down the excess all the way around the front, even under your pits and lock down with your belt. Then bend over a bit with shoulders together again, have someone yank down shirt below belt and arch back making sure everylast bit of slack is out.
A moderate shirt should give you at least 50 lbs if not 100 fairly easily if you know how to manipulate it some. Those Inzer HP whatevers won't give you much nor will they retain their elasticity. If your going to eventually compete with an open back, cut that one right down the center. To see what it can do, after it's been cut, pull collar down to wear it rides midway down your front delt, for a little bit more, roll the collar itself underneath to wear it's just above your armpit creases.
If you bench elbows out and don't start tucking them, you'll never get as much out of a shirt cuz no matter how low it is, once your under the weight, the shirt will rise right up to your throat and you'll loose the benefit of the shirt as soon as you flare those elbows. Yes you flare out on the lockout but tuck on the bottom for clarification, if your flared at the bottom, that shirt will flatten you out and rise up to your throat or your chin.
Hope this helps a little...