ABF was flying rehabbed DC-9s in such a operation and had an instrument failure at an outstation. They had to hire a LearJet to deliver a replacement. This was the incentive for them to investigate retrofitting DC-9s with glass cockpit - lower DOC plus reliability.
So you re saying that a glass cockpit might be a good idea? as you can see above, it was suggested that a glass cockpit may be a rather bad choice to lower DOC.