Las and et al,
See link below where the Mishkenos Yaakov explains how the Midbar and Mishkan was a RhR according to the Shu”A.
http://www.hebrewbooks.org/pdfpager.aspx?req=1095&st=&pgnum=133
See below link (on top of the left column) how he again explains that even if the 600K are right next to the road/place, according to the Shu”A it needs to be Bokim/Ovrim physically every single day on the very road in concern. That is why Machnei Yisrael was not concidered rh”R, based on the above rishonim.
http://www.hebrewbooks.org/pdfpager.aspx?req=1095&st=&pgnum=134
See how he explains the shitas haRitva ( 600k either needs to be a ‘Maavor’ /’Derech’ to the road in concern or “at least” residing within the city.):
http://www.hebrewbooks.org/pdfpager.aspx?req=1095&st=&pgnum=135