These routes can be flown under VFR with the clearance containing a level band rather than a fixed level i.e. "Not above altitude 3000ft".
That's a big space to give? Isn't greater capacity possible when you assign one aircraft for 1000ft, the next one for 1500, 2000, 2500, and 3000? (Flyable if the pilot can maintain the clear-of-cloud requirement)