Are you sure you want to use a litho-type ortho film if you want a long tonal range? Why not a lower contrast ortho film? As you noted, litho-type films are designed for high contrast and a relatively short scale. You can reduce contrast with low contrast and/or dilute film developers (wouldn't suggest print developers as they are generally much too active to produce low contrast even with general purpose films).

Alternatively you may want to try Ilford Ortho Plus.