That's a lot of rocking and swaying forwards and backwards. Any chance you could set the bar against your shins and drag it on the shins slightly as you pull? You don't have to skin your shins, just keep constant contact with them. Imagine leaning back as you pull, this should keep the bar against your shins. Also, maybe try keeping your head/neck in a neutral, position, think head pulled back and a double chin. Small adjustments, but otherwise, congrats on your PR.