Why cannot this elastomeric be a one-piece tapered tube. It would be produced inside out. The torque tube would be coated with an epoxy. Then the elastomeric tube would be rolled on, starting at the small diameter end.

Alternative Idea: Perhaps produce it right side out over a tapered mandrel, which has a non-bonding surface. The elastomer is removed by rolling back the larger end and pulling it toward the smaller end. The elastomer is now off the mandrel but is inside out. To install it on the Torque Tube, the elastomeric tube would be rolled on, starting at the small diameter end.