A question about the Presidency.....

Suppose an unmarried man was elected to the Presidency.Obviously,this mean there would be no wife to serve as First Lady.Now,I understand there has been a bachelor President before,James Buchanan.Ive read that he solved the issue by having his niece fill the role.But suppose the modern day hypothetical bachelor President had no family left,or didn't have any that was willing to do the job.Would he 1) literally hire an outside woman unrelated to him for the position or 2) simply serve his term without the position being filled?What would be the protocol?