I cannot tell the workings of your chute for the squeeze so maybe it will not work but if I was to lower the top of the sheeting I would want to lower the whole side so that the bottom of the sheet was within a couple inches of the ground.  A properly adjusted squeeze i s great but that gap at the bottom is what calves are working for when they put there head down, do a summersault and get turned around in the chute. eliminating light at the bottom helps with this.