LOL. The very reference is to the sin sacrifice which was carried out of the camp and burned "with his dung". And yes, the offering was a substitute for the offerer.Hebrews 13:13 - So, let us go out to Jesus outside the camp, bearing His reproach.
That's not substitution.
Expiation is active, not passive. Sin isn't expiated by the mere virtue of Christ's death. He took our sins upon Himself, and He died a sinner's death, as Paul said, quoting the law, "Cursed is everyone that hangs on a tree."
That cross was righteous judgment...judgment upon our sins in the body of Christ.