I'll chime in here..I own a Metal Ace Suit (and Metal Pro Briefs) so I know exactly what you need to do. This is basically what I was going to say..but would add a few things.
Not sure what you got going on with getting hurt when you go narrower but you are hunched over big time with that grip you have. It's making you lean forward to keep the bar on your back, which is making your squat harder. You need to keep your chest up and look ahead and up a bit. In the second video it appears that you aare looking down. The body goes where the head leads it...
I grip the bar with my pointer finger on the rings and I use a pinkyless grip (only 3 fingers are holding the bar). The pinkyless grip makes it feel much nicer for some reason. This will make your whole back tight and make the weight easier. Somehow you have to make this happen if at all possible and get your elbows under the bar.
Yes..and it's impossible to get "big air" with that weight on your back and trying to breathe into the chest- hence the 'shrugging'. You should breathe in to the gut and then push that gut into the belt. This makes a stable core to push big weights
This is especially true when wearing the ace suit..The ACE suit/briefs are kind of like canvas in that they will stop you dead in the hole, only unlike canvas the ACE has 'pop', at least the suit does because of the straps. I don't notice the pop near as much when I have the straps down to be honest but it does stop you at a certain height depending on how tight they are. Anyways.. the ACE stuff works best with a wide stance. Your toes should touch the bottom bars of that rack in the first video. And then sit back and down. Try a wall squat..
this will get you the right form.
lastly look at where your belt is positioned in the videos. They are worn very low. You'll get WAY better support if you place it higher on the torso. IE just under the ribs.