Your post about making replacement of the PVC tube very easy got me to thinking about how this could be done.  What if instead of planning to replace the PVC tube, a simple sacrificial flanged plastic bushing was made to fit into the PVC pipe on the bottom face of the anchor locker?  Since the bushing would have a  smaller ID than the PVC it would take all of the side loads and eliminate essentially all of the wear on the PVC pipe?  It might be good to make the ID of the PCV tube a little larger to allow for the hole in the sacrificial bushing to be of sufficient size.  I believe that the base hole in the windlass is already serving the function of the bushing at the top so only a bushing at the bottom would be needed.  Perhaps the bushing could be made to screw in place to eliminate having to install many fasteners in that difficult area to work?