Surprised nobody has mentioned FedEx. OKC-MEM, company metal, can book JS 21 days in advanced. Typical schedule of week on/week off type of flying. Seniority = 777 = 1 longer (8-12) day trip a month. Or airline deadheads not the front and/or back of a trip that you can deviate from and use the money to buy a ticket from OKC vs. MEM to the first operating city/leg.

Or, Delta.