Rabbi Dr. John Fischer writes in one of his chapters (entitled "Yes, We Do Need Messianic Congregations!") of Zondervan's 2003 release How Jewish Is Christianity?: 2 Views on the Messianic Movement (p. 54):
The phrase "outside the camp" ... is misconstrued and therefore misused. "Outside the camp" in Exodus 33:7 describes the very heart of Judaism, the original Test of Meeting. when God revealed himself to his people at Mount Sinai, he met them "out of the camp (Exodus 19:17). "Outside the camp" is the place of ceremonial cleansing with the ashes of the red heifer (Numbers 19:9) and the location of significant elements of the Yom Kippur (Day of Atonement) ritual, as the bodies of the sacrifices are taken here and the scapegoat is released here (Leviticus 16:21-22, 27). So "outside the camp" serves as the core of Judaism and does not imply a separation from it.