In rural mortgage areas the agency may make and undertake commitments to make construction loans and mortgage loans to finance owner-occupied residential structures without the participation of a qualified mortgage lender if no qualified mortgage lender will participate in financing such residential structures as provided in Article 2 (commencing with Section 51125) or Article 3 (commencing with Section 51150) of this chapter, or if the board determines that the agency can initiate or service loans directly at less cost than through use of a qualified mortgage lender.