I do them onto a medicine ball. Wouldn't the deep depth actually make the glutes and rest of the post chain a pretty big factor in the lift?
It would help but I suspect the emphasis on the posterior chain still wouldn't be close to the back squats. This is due to the angle of the hip joint and the rotation that occurs at the pelvis in a back squat. The positions of a backsquat places the hamstring under much greater tension than for a front squat.