Ty the bladder is always going to crush somewhat due to the pressure inside the shock. As for getting the air out take your time and build it slowly. When you first start to fill the shock the oil will not flow underneath the piston so you will have a large air gap under the piston. Fill the shock part way with oil then move the piston up through the oil. When you pull the piston back down all the air underneath will come out in bubbles. Give the bubbles time to rise to the top and exit the oil. I'll usually work the piston a few times during this to make sure I got all the air out from under the piston. Then fill the shock the rest of the way and work the piston some more to see if any more air bubbles appear. Once the air bubbles are gone then put on the bladder and shock cap.