At the end of Parashat Emor is the story of the “son of the Israelite” who blasphemied HaShem’s name because HaShem returned His judgement to Moshe that the man did not have a right to set up camp with the tribe of Dan, as he would wish, since his father was an Egyptian. Where, then, was he supposed to set up camp, and why?
He like the eirev rav was a member of Klal Yisrael as a convert just like everyone else who had been at the revelation on Har Sinai. However, since his father had not been one of the tribes, he did not belong to any tribe. Thus he was supposed to live with those who were not members of a tribe. Note that the definition of a Jew is one whose mother is Jewish back to the revelation at Har Sinai. This means that everyone who was at the revelation was Jewish including the eirev rav. The members of the tribes were based on the fathers membership back to the original sons of Yaakov.