Looks like that's a standard barbell, in which case holy crap that's gotta hurt for zerchers. The foam is a good idea. Another approach (if you have Olympic plates) is to use an axle. The wider bar diameter distributes the load better.
Never did a zercher squat, but did a LOT of seated zercher axle good mornings while I was rehabbing my ACL, and never felt too much pain with the axle.
Also, it's a great workout if you ever want to blow out all of the capillaries from one shoulder clear across your chest and face to the other shoulder.