Yeah, the bar tampon will make it almost impossible to do low bar squats as it will make the middle of the bar thicker and then the bar won't be able to rest on your deltoids like it's supposed to.
If you pull your elbow straight back you should be able to feel a groove in the back of your shoulder which is where the bar should sit.
I didn't like the rules you gave me, so I made some of my own.
Strong people are harder to kill than weak people, and more useful in general. - Mark Rippetoe