In carrying out the provisions of sections 47–2 to 47–6 of this title, the Secretary shall take care that there be no opportunity for any personal influence by an employee of the Department of the Interior upon the availability of housing for other such employees or employees of persons in a contractual relationship with the Department. In the selection of lessees and sublessees, the issuance of leases and subleases, the establishment or ¹ rental values, and the acquisition of any unexpired term of any lease or sublease, the Secretary shall act through an agent or agents appointed by the Secretary from among associations, corporations, or natural persons having no material, financial, legal, or equitable interest in the action proposed, other than a reasonable fee for their services.