Did you ever come across the type with a fitted diffuser, ring (for want of a better description) at each end to support the tube and a fixed BC holder at one end? The idea was to slide the tube the whole length, locate in the ring then locate in the BC and turn to the slots then push and turn, all supposedly done from the free end then add the loose BC and then slide the cover on without cutting the cable?
A very long time ago, but I half remember something similar..

